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Notes: 1,2,3-Triazabutadienes. VII. Investigation of the Mechanism of the Photochemical cis-trans-Isomerization of 1-Aryl-3-[3-methyl-benzthiazolinyliden-(2)]-triazenesThe direct photoisomerizations of substituted triazabutadienes are investigated. The quantum yields do not considerably depend on substituents in the phenyl-group of triazabutadienes, on the wavelength of irradiation light and on the solvent. The quantum yields of the cis→trans-transformation are always higher than the quantum yields of the back reaction. The sums of quantum yields approximate 1. At low temperatures the quantum yields of photoisomerization become smaller in a significant way. With flash photolysis it is not possible to prove triplet state of triazabutadienes. Triplet quenchers have no influence on photoisomerization. The mechanism of the photochemical cis-trans-isomerization of triazabutadienes is discussed.

Notes: α-Substituted Phosphonates. XXX. Dealkylation of Phosphonic Acid Esters with Labile Functional Groups by Trimethylsilylbromide

Notes: Polyfunctionalized N-Tensides. I. Nucleophilic Substitutions with Bischloronitrosocompounds. 1. Reactions with Amines, Mercaptans and Sodium AzideChloronitrosation of alkenes gives bischloronitrosocompounds 1, which react with amines to α-aminooximes (2 and 4), with mercaptans to α-alkylthiooximes 11, and with sodium azide to α-azidooximes 8. Reduction with LiAlH4 gives vicinal substituted diamines (6, 7, 10) from α-amino-or α-azidooximes (2, 4, 8) and β-alkylthioamines 13 from α-alkylthiooximes 11.The determination of E- or Z-configuration in the α-substituted oximes is discussed.

Notes: Pyrylium Compounds. XIV. The Light Absorption of 1,2-Benzoxalenes (Indeno[2,1-b]pyrans)The iso-π-electronic relationship between azulene A and the heterocyclic pseudoazulene B is reflected by the same dependence of the N—V1 transition from the substituents: Many examples (1-27) show that pseudo-azulenes of the 1,2-benzoxalene type (indeno[2,1-b]pyran) C undergo a bathochromic shift by alkyl substitution at C3 and C6, but an hypsochromic shift by alkyl substitution at C7. Second order substituents effect an opposite influence (examples 92-98). The conjugative effect of substituents causes a bathochromic shift in all positions (examples 49-58), which may rise to a remarkable amount with the extension of the conjugated system (examples 59-91). The relations obtained correspond to the results of quantum-chemical calculations (examples 28-48).

Notes: Fatigue Products of Photochromic 2-(2′,4′-Dinitrobenzyl)-pyridineUnder prolonged irradiation or frequent repetitions of its photochromic cycle, 2-(2′,4′-dinitrobenzyl)-pyridine 1 shows fatigue phenomena both in solid state and in solution. These phenomens  -  yellow discoloration, depression of the melting point, decrease of band intensity of the coloured form, shorter lifetime of the coloured form  -  are caused by irreversible redox processes and subsequent reactions at the methylene and ortho-nitro groups which are essential for photochromism. Azomethine 2, ketone 3 and amine 4 are isolated as the major fatigue products.

Notes: Synthesis and Reactions of 1,3-Azaphosphorinane-2-thionesAminopropylphosphines, R—P(H)—(CH2)3—NH2, react with carbon disulfide to give 1,3-azaphosphorinane-2-thiones. In presence of strong bases the title compounds are converted by alkyl halides into 2-alkylthio-3, 4, 5, 6-tetrahydro-1, 3-azaphosphorines whereas in absence of bases quaternization at the phosphorus atom occurs to give 2-thiono -1,3-azaphosphorinanium salts. The structures of the compounds prepared are elucidated by IR. 1H-n.m.r. and mass spectra.

Notes: Derivatives of Halogenated Aldehydes. XIV. Reactions of 1,2,2,2-Tetrachloroethyl Isocyanate1,2,2,2-Tetrachloroethyl isocyanate 2 reacts with alcohols or phenols to form the N-tetrachloroethyl-O-alkyl(aryl) urethanes 3-6. With thioalcohols and thiophenols the corresponding thiourethanes 11-12 are obtained. In these compounds the chlorine in position 1 can be substituted by treatment with a nucleophilic compound in the presence of a base by way of an elimination addition mechanism. In these reactions the compounds 7-10 and 13-14 are formed. Amines attack 2 at both active centres to give the substituted ureas 15-18. Diphenyl amine, some carboxylic acid amides and benzazoles, however, react only with the isocyanate group to form the compounds 19-25. Reactions of 2-amino-benzazoles, 2-amino-pyridine and amidines with 2 yield the heterocyclic compounds 26-31.

Notes: Pyrazolone Derivatives. V. U.V.-Spectroscopical and Photochemical Behaviour of N-mono and N,N-disubstituted 4-Aminomethylene-Δ2-pyrazolinones-(5)U.V.-spectra of N-mono and N,N-disubstituted 4-Aminomethylene-Δ2-pyrazolinones-(5) 1a-j and their dependence on solvent and temperature are discussed. N,N-disubstituted and N-monosubstituted 4-aminomethylene-3-methyl-1-phenyl-Δ2-pyrazolinones-(5) show a Z-/E-isomerization of the exocyclic C=C-double bond at low temperatures. Compared to the N-monosubstituted compounds the compound 1j exhibits a strong interaction in the E-configuration between the aminomethylene-substituent and the methyl-group at the parazolone-ring.The Z-/E-isomerization depends on solvent polarity. With increasing solvent polarity the energy of activation of thermic E-/Z-isomerization is decreased.A low temperature cell is described.

Notes: Pyrimidinderivate und verwandte Verbindungen. VIII. Neue Synthesemöglichkeiten für 3,5-Diaminopyrazole, 2-Aminopyrazolo[1,5-a]-pyrimidine und 5-Aminopyrazolo-[1,5-a]-pyrimidineWährend die 3,5-Diacylamidopyrazole 2a-c durch Umsetzung von 3,5-Diamino-4-phenylazopyrazolen 3 mit Schwefelsäure und Fettsäuren erhalten werden, entstehen die 3,5-Diaminopyrazole 1 beim Erhitzen der Pyrazole 3 mit Schwefelsäure.2-Amino-6,7-dihydro-5-methyl-7-oxopyrazolo [1,5-a] pyrimidin (4) erhält man durch Entfernung der Phenylazogruppe des leicht zugänglichen 3-Phenylazoderivates 6.Die 5-Aminopyrazolo [1,5-a] pyrimidinderivate 12a-c erhält man in guten Ausbeuten durch Reaktion der 5-Aminopyrazole 10a-c mit Diethyl-β-amino-β-trichloromethylenmalonat 11a. Durch Reaktion von 11b mit 10b entsteht das 5-Amino-6-cyanopyrazolo [1,5-a] pyrimidinderivat 12d.

Notes: Absorptionsspektren einiger ChinonanileElektronenabsorptionsspektren einiger Chinonanile wurden in organischen Lösungsmitteln unterschiedlicher Polarität untersucht. Die Spektren werden in Abhängigkeit von Mediumeffekten und der Molekularstruktur diskutiert. Die pK-Werte der Verbindungen wurden durch Spektralmessungen in Pufferlösungen durch Veränderung des pH-Wertes bestimmt. Die wichtigsten IR-Banden werden bezüglich der Molekularstruktur diskutiert.

Notes: Acylketene S,S- and Acylketene S,N-acetals as Buildingsets for Heterocycles: 5-CyanopyrimidinesAcylketene S,S-acetals 1 react with amidines, guanidine or S-alkylisothioureas in the presence of triethylamine to give 4-methylthio-5-cyanopyrimidines 4-6. 4-Anilino-5-cyanopyrimidines 7 have been synthesized from the acylketene-S,N-acetals 2 under similiar conditions. The treatment of 1 with guanidine and acetamidine, respectively, in alcoholic sodium ethoxide solution yields 4-ethoxy-5-cyanopyrimidines 10. The i.r.- and 1H-n.m.r.-spectra of the synthesized compounds are discussed.

Notes: 1,2,3-Triazabutadienes. IX. 15N-NMR-spectroscopic Investigations of Cis-Trans-Isomeric 1-Aryl-3-[3-methylbenzthiazolinyliden-(2)]-triazenes and -triazenium-saltsThe 15N-chemical-shifts and coupling constants of systematically 15N-labeled cis-trans-isomeric 1,2,3-triazabutadienes 1a-c and triazenium-salts were determined and discussed with respect to the steric and electronic structure of the compounds. The chemical shifts correlate with the π-electron density calculated in PPP-approximation. The similarity of the chemical shifts and coupling constants of the respective alkylated and protonated compounds proves the preferred protonation of the trans triazabutadien chain in N1-position.

Notes: Selective Reactions of Carbohydrates with Isocyanates6-O-Arylcarbamoyl-D-galactose dialkyl dithloacetals 2a-n are prepared by selective reactions of D-galactose dialkyl dithioacetals with aryl isocyanates in pyridine. Some of them are acetylated to give the 2,3,4,5-tetra-O-acetyl derivatives 3a, b, i-m. The structures of the compounds 2 and 3 are proved by further synthesis from 1,2;3,4-di-O-isopropylidene-D-galactose or 2,3,4,5-tetra-O-acetyl-D-galactose diethyl dithioacetal, respectively.

Notes: Photochemistry of Aminoketones. III. Structures and Photochemical Behaviour of β-Aminovinyl-phenyl-ketones in Solvents of Different PolaritySpectroscopic data of ten selected β-aminovinyl-phenyl ketones Ph—CO—CH=CR1—NR2R3 in polar and nonpolar solutions, respectively, are discussed and the structures assigned. The apparent photochemical inertness of these compounds in alcoholic solution and the irreversible reactions of some enaminoketones in nonpolar medium are explained in terms of relations between the compounds and the polarity of the solvent.

Notes: Infrared Intensity Measurements, Dipole Moment and 1HNMR Studies on Selected Chromium Tricarbonyl Complexes of Dinuclear ArenesIntegrated intensities of v(CO)vibration bands in a series of mono- und di(tricarbonyl-chromium)-π-complexes of substituted and unsubstituted dinuclear arenes of the Ar—C—Ar or Ar—C—C—Ar type have been measured in tetrahydrofurane solution. The bond angles α between the CO groups have been determined by the method of BECK. The values of these angles range from 83° to 90° and do not permit decisions concerning the intramolecular interactions between two tricarbonylchromium groups.On the other hand a band analysis showed that there are two A1 modes in the spectrum of benzylbenzene di(tricarbonyl-chromium), whose intensity ratio is both temperature and solvent dependent. One can assume preferred conformations in the C(H2)-arene bond due to the neighbourhood of the tricarbonylchromium groups. In connection with dipole measurements a ratio of conformers could be estimated.1HNMR data showed that there is a hindrance of the free rotation, already present in benzylbenzene(tricarbonyl-chromium).

Notes: Reaktion von Aryliden-diphenylsulfiden und -diphenylsulfonen mit Diazoalkanen

Notes: Spektrophotometrische Untersuchungen einiger Arylidenderivate von Benzoe- und Salicylsäurehydraziden in Pufferlösungen

Notes: The Nature of the Transition Metal to Carbon σ-bond. II. Mass Spectrometric Investigations of Mono-organyl-Transition Metall Complexes of Phthalocyanine and SalenIn the mass spectra of monomethyl and monophenyl complexes of Fe(III) and Co(III) phthalocyanines (RMPc) there are observed peaks at higher mass numbers than that of the molecular ion which are described to products containing more than one organyl group.It is concluded from the mass spectra and the ionization efficiency curves of the ions R2MPc+, RMPc+ and MPc+ that, due to the high temperature in the inlet system of the mass spectrometer, in the solid state a loss of the organyl residue R and an attack of the radicals at the phthalocyanine ring takes place.The mass spectra of methyl- and phenyl-cobalt(III)-salen do not contain any peaks at higher mass numbers than the molecular ion. The problems of mass spectrometric determination of the strength of the transition metal to carbon σ-bond are discussed.

Notes: Synthesis of 6-Ethyl-7-aryloxy(thio)methyl-4-hydroxy-quinoline-3-carboxylic EstersBy etherification of phenoles and thiocresol with 2-ethyl-5-nitrobenzyl chloride 2 to 1-ethyl-2-aryloxy(thio)methyl-4-nitrobenzenes 3, reduction of 3 to the corresponding amino compounds 4, condensation of 1-ethyl-4-amino-2-aryloxy(thio)methyl-benzenes 4 with ethoxymethylen-malonic ester to substituted aminomethylenmalonic esters 5 and thermal cyclization potential coccidiostatic 6-ethyl-7-aryloxy(thio)methyl-4-hydroxyquinoline-3-carboxylic esters 6 have been synthesized. The structure of substituted quinolines was examined by n.m.r.

Notes: Polarographisches Verhalten von 2-Benzoyl-3-thionaphthenonDas polarographische Verhalten des 2-Benzoyl-3-thionaphthenons (I) in wäßriger, ethanolischer Pufferlösung zeigt bei Veränderung des pH-Wertes, daß die Carbonylgruppe des heterozyklischen Teiles im sauren und neutralen Medium durch einen Zweielektronenprozeß reduziert wird.Im stark basischen Bereich ist ein stabilisiertes Enolat die reduzierbare Form der Verbindung I.

Notes: Thermodynamische Studien einiger Seltenen-Erde-Chelate des N-Acetylacetonvalins

Notes: Silicium-(IV)-Komplexe von β-Diketonen und aus Aminoalkoholen synthetisierten Schiffschen Basen

Notes: The Diazotization of Some Weakly Basic Aromatic Amines with Nitrosylhydrogensulfate in Sulfuric Acid

Notes: Detailed cation scavenger studies in pulse-irradiated pure, liquid CCl4 reveal that the 500 nm absorption has both, neutral and cationic characteristics, and that CCl4+ must be the precursor. It is shown that all experimental results are compatible with the following ion neutralisation mechanism: CCl3+ + Cl- → (CCl3+ · Cl-) → CCl4.The 500 nm band is assigned to the CCl3+-cation (free or complexed). Its neutralisation therefore does not occur on ion recombination, but is delayed by the life time of the ion pair: τ½ (ion pair) = 33 ± 3 ns at -22°C with activation energy of 10.9 ± 2.1 kJ/mol. Possible reasons for the ion pair stability are briefly discussed.

Notes: Preparation of styryl derivatives of 2-phenyl-imidazo [1, 2-a]pyridine2-(p-Tolyl)-imidazo [1, 2-a]pyridines and 7-methyl-2-phenyl-imidazo [1,2-a]-pyridines can be converted, in dimethylformamide, on reaction with anils of aromatic aldehydes in the presence of potassium hydroxide or potassium t-butoxide, into the corresponding 2-(stilben-4-yl)- and 2-phenyl-7-styry1-imidazo [1, 2-a]-pyridines (‘Anil-Synthesis’). The 2-(p-tolyl)-imidazo [1,2-a]pyridines react far less readily than the 7-methyl-2-phenyl-imidazo[1,2-a]pyridines.

Notes: Preparation of styryl derivatives of 2-phenyl-4H-1,2,4-triazolo [1,5-a]pyridine7-Methyl-2-phenyl- and 2-(3-chloro-4-methylphenyl)-4H-1,2,4-triazolo[1,5-a]-pyridines react with anils of aromatic aldehydes in the presence of dimethyl-formamide and potassium hydroxide at 20-45° to yield the 2-phenyl-7-styryl- and 2-(2-chloro-stilben-4-yl)-4H-1,2,4-triazolo [1,5-a]pyridines respectively (‘Anil Synthesis’). Further, the Schiff's bases derived from o-chloroaniline and 2-(p-formyl-phenyl)- and 7-formyl-2-phenyl-4H-1,2,4-triazolo [1,5-a]pyridine yield, with methyl- and with p-tolyl-substituted heterocycles, the corresponding heterocyclic substituted styryl and stilbenyl derivatives.

Notes: The triplet-triplet absorption spectra of p-N, N-dimethylnitroaniline, 4-nitro-p-terphenyl, 1-amino-4-nitrofluorene, 5-nitroacenaphthene, trans-1-(4-methoxy-phenyl)-2-nitroethylene (MeONS), and trans-1-(4-dimethylaminophenyl)-2-nitroethylene (DANS) in EPA glass at 77 K are reported, together with molar extinction coefficients and PPP-SCF-MO-CI calculations. The two nitrostyrenes, MeONS and DANS, have been examined in fluid media at room temperature using nanosecond laser photolysis, and their triplet lifetimes found to increase substantially with increase in solvent polarity and charge-transfer character of the compound. This is interpreted in terms of the diradical/zwitterionic nature of the triplet state affecting the T1-S0 energy gap at the 90° twisted configuration of the olefinic linkage.The decrease in both the triplet yield and the fluorescence yield of DANS with increase in solvent polarity is explained by the intervention of an internal conversion process involving a rotation of the dimethylamino group in the lowest singlet excited state.

Notes: Delayed fluorescence (DF.) spectra of 1,2-benzanthracene, fluoranthene, pyrene, and chrysene in methylcyclohexane were measured at -80° up to the wavenumber corresponding to the energy of two triplets. With all four compounds a weak DF. Sn → S0 from the highest state Sn accessible by triplet-triplet annihilation (TTA) was found. Lifetimes of Sn calculated (a) from the ratio of the DF's Sn → S0 and S1 → S0 and (b) from the difference in line-width of the 0,0-transitions Sn,0 ← S0,0 and S1,0 ← S0,0 agree reasonably well. This indicates that population of the highest accessible excited singlet state is the dominating primary process in the excited singlet channel of TTA. There is no evidence for excimer formation being the first step in TTA. DF. spectra extend up to the energy of two triplets. With pyrene the intensity distribution in the hot-band region of the DF. S2 → S0 suggests that in TTA the same vibrational selection rules are valid as in one-photon absorption S2 ← S0 and that vibrational relaxation within the S2 manifold is slow compared with internal conversion S2 ↝ S1. The experimental technique is described in detail and experimental difficulties arising from impurities and photoproduct formation are discussed.

Notes: During UV.-irradiation of aliphatic carboxylic acids and esters in aqueous and nonaqueous solutions various alkyl and acyl type radicals derived from parent compounds and solvents have been observed by ESR.-spectroscopy. The structures of the radicals point to α-cleavage, β-dehalogenation and photoreduction as major photolytic processes of carboxylic acids and esters. The relative contributions of these processes to the overall photodecompositions depend on the carboxyl substituents, on solvent and temperature. Similarities of carboxyl and carbonyl group photochemistry are discussed.

Notes: The Synthesis of Actinioerythrol, Violerythrin and other 2,2′-Dinor-carotenoids2,2′-Dinor-carotenoids including the naturally occurring actinioerythrol (1) and the blue carotenoid violerythrin (2), as well as 2,2′-dinor-rhodoxanthin (25) and 2,2′-dinor-zeaxanthin (27) and others have been obtained by total synthesis.

Notes: On the Mechanism of Radiationless Deactivation of the First Excited Singlet State of 2-Alkyl-indazolesThe temperature dependence of the quantum yields of fluorescence (ΦF), intersystem crossing (ΦT) and photoreactions (ΦR) have been measured for several neutral and protonated 2-alkyl-indazoles. The experimental data (Fig. 1 and 3) can be interpreted in terms of the reaction schemes 1 and 2 with temperature independent constants for fluorescence emission and intersystem crossing and temperature dependent photochemical primary processes. Whereas at low temperatures the sum of the quantum yields of fluorescence and intersystem crossing equals 1, at higher temperatures a very efficient radiationless deactivation process takes place (Table). Based on kinetic and photochemical data it is concluded that this deactivation proceeds via a hypersurface crossing (Fig. 2) or hypersurface touching (Fig. 4) in the course of the photochemical rearrangements 1 → 2 and 4 → 5 respectively.Similar mechanisms are expected to be responsible for the unusual internal conversion in other heterocyclic compounds.

Notes: A kinetic analysis of the thermal rearrangement of linalyl trimethylsilylether (1b) shows that four diastereoisomeric 1, 2-dimethyl-3-isopropenyl-l-cyclopentyl trimethylsilyl ethers (2b-5b) are formed directly in parallel first order reactions. Kinetic analysis of the thermal rearrangement of dehydrolinalool (6) shows that two diastereoisomeric 1-methyl-2-methylidene-3-isopropenyl-1-cyclopentanols (7 and 8) are formed in parallel first order reactions. The configurations of 7 and 8 are determined by correlations with the known iridenols.

Notes: The unimolecular fragmentations of internal energy selected allene molecular ions (1+) have been investigated by photoelectron-photoion coincidence spectroscopy. The energy dependence of the branching ratio between the two most important fragmentation channels is reported, together with values for the kinetic energy release during fragmentation. Loss of an hydrogen atom from 1+ is interpreted to proceed via two paths, yielding different isomeric forms of C3H3+ with different kinetic energy release values.

Notes: The maximum of the d.c. conductivity of single crystals of the title compound ((TTT)2-I3), grown by cosublimation, is shown to be at about 35K. The ratio of the b-axis (needle axis) conductivity at the temperature of its maximum (Tm ≅ 35 K) and its value at T = 300 K (normalized conductivity σb″(Tm)/σb″(300)) is strongly sample dependent. Values for σb″(Tm)/σb″(300) as high as 8 have been obtained. From 300 K to about 120 K the conductivity σb″ is proportional to T-1.3. in the temperature interval 40K≤T≤120K we found: σb″∝T-1. On the low temperature side of the maximum (6K≤T≤20K) the conductivity is proportional to Tα, with α ranging from 2 to 2,5. It is shown that impurities, misfit of the stoichiometry and/or physical sample quality (crystal perfection) drastically shift the minimum of the resistivity to higher temperatures (Fig. 5), thereby altering also the temperature dependence of the resistivity on both sides of the minimum. Our crystallographic data difference from the results published by Isett et al. and Buravov et al. (Table 1) with regard to the iodine spacings. We argue that the polarisability of the I3-1 ions in their chain direction contributes significantly to the high conductivity (σb″=1000 to 1000 Ω-1 cm-1) along the crystallographic b-axis (needle axis).

Notes: Near UV. irradiation of N-methyl isoindole (1) in deaerated solution has yielded two constitutionally isomeric [π4s+π4s] dimers 3 and 4 (Scheme 2). No transient or stable photoisomers of 1 were detected. The photodimers were reconverted to 1 both by pyrolysis and photolysis. The photocleavage of dimer 3 proceeds (predominantly) by anonadiabatic pathway yielding 1 in its electronic ground state. Prolonged pyrolysis of 1 afforded 11H-indeno [1,2-c]-isoquinoline (5) as a major product.

Notes: 3,4-Dimethoxyfuran: Properties, Calculations and some Substitution Reactions3,4-Dimethoxyfuran (3,4-DF) is much more reactive than furan itself. We present experimental details for the synthesis of this useful compound in 50-100 g batches. 3-4-Dibenzyloxyfuran has also been prepared. Quantum mechanical calculations by PPP-and CNDO-methods analogous to furan itself gave the following information (compared with furan): enhanced negative partial charge at C(2) and C(5), higher acidity at α-position, a stronger and at the same time inverted dipol moment. In accordance with the calculations, 3,4-DF can easily be substituted by weak electrophilic reagents, e.g. in a typical Mannich reaction. The bis-amino compound 8 is produced in good yields. Lithiation by butyl-Li leads to mono- or di-substituted products. The mono- and di-Li-3,4-DF have been used for the preparation of various acylated and alkylated 3,4-DF derivatives.By acid hydrolysis of 3,4-DF crystalline 4-methoxy-3 (2H)-furanone has been prepared.

Notes: The photochemical reactions of different allyl aryl ethers (Scheme 3) were investigated in hydrocarbons (Chap. 3.1) and in alcoholic solvents (Chap. 3.2). The composition of the photoproducts depended very much on the nature of the solvent. Irradiation (3-95 h) of different methyl substituted allyl aryl ethers (1, 3, 5, 7 and 11) with a low pressure mercury lamp (λEmiss. = 254 nm; 6 or 15 Watt) under argon (quartz vessel) resulted in the formation of 2-, 3- and 4-substituted phenols, dienones and products of consecutive reactions (Tables 1-4 and 6). The results suggested that all products were formed by homolytic cleavage of the C—O bond in the singlet state of the ethers to intermediate radical-geminates (Scheme 5) followed by radical recombination of the two fragments. No products were formed by concerted processes (Table 5, Schemes 5 and 6).Upon irradiation of allyl aryl ethers lacking alkyl substituents at position 4 (1 and 5) in protic solvents, mainly 2- and 4-allylated phenols were obtained (Tables 1 and 4); 3-allylated phenols were formed only in small amounts (0.02%). However, in aromatic hydrocarbons or cyclohexane 3-allylated phenols were obtained from 1, 5 and 11 in significant amounts (3-11%; Tables 1, 4 and 6). E.g., upon irradiation of allyl-2,6-dimethyl-2,4-cyclohexadien-1-one (6) besides 3- and 4-allyl-2, 6-dimethyl-phenol (23 and 24). Irradiation of 5 in methanol afforded 23 and 6 only in traces, whereas 24 was the main product.

Notes: Nucleophilic alkylation of aromatic nitro compoundsAromatic nitro compounds may be alkylated in o- or p-position by treatment with alkyl lithium or alkyl Grignard reagents.

Notes: The theory of solvent-induced shifts of the absorption and fluorescence band spectra of a solute is well known and has been tested for a multitude of systems. However, there are only few applications to polymers. By a direct comparison of the spectral shifts in liquid solvents with those in polymers it is possible to determine the microenvironment of the solutes in polymers within the frame of this theory. Polyethylene terephthalate as fabric and film was chosen as model polymer. The spectral shifts of 15 fluorescing solutes in this polymer as well as in 10 solvents with widely differing refractive indices n and permittivities ∊ were measured and fitted to the equations given by the theory of the solvent effect. It is found that interactions with the permanent dipoles of polyethylene terephthalate may be neglected within the limits of accuracy attainable for this polymer and the chosen solutes. Dispersion forces dominate the solvent effect. The refractive indices effective at the site of the solute molecules are n = 1.66 for the fabric and n = 1.70 for the film.

Notes: Addition reactions on the alicyclic double bond of eburnamenine and apovincamineThe addition of alcohols, amines or thiols on the 14, 15-double bond of (-)-eburnamenine (3a) or (+)-apovincamine (9a) yielded the corresponding analogues of vincanol (5b-h), epivincanol (7b-d), vincamine (10b-e) and epivincamine (11b-g) with varying stereoselctivity. The reaction was achieved by addition of hydrogenbromide at -78° followed by nucleophilic attack, or in the (-)-eburnamenine series also by direct addition of alcohols and thiols under acidic conditions. Without exception the analogues of epivincamine (11a-g) exhibited two carbonyl absorption bands in thier IR. spectra. (-)-Eburnamenine (3a) was obtained from (+)-apovincamine (9a) in a simple one pot reaction.

Notes: On the Temperature Dependence of the 13C-NMR. Spectra of [5-6-η-(1Z,5E)-Cyclooctadien] and of (lZ, 5E)-CyclooctadieneThe activation parameters of the conformational ring inversion process (simultaneous rotation around the C(3), C(4) and C(7), C(8) bonds; cf. Scheme 1) of the title compounds (1 and 2, respectively) have been determined between 275 L and 155 K by a complete line shape analysis of the temperature dependent proton noise-modulated decoupled 13C-NMR. spectra of 1 and 2. The temperature dependence of the rates (k(1) and k(2), respectively) of the inversion process can be described by the following equations (no influence of the solvents was observed; Ea in J/mol): \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} k(1) = 10^{13,02 \pm 0.35} \,\exp (- (42010 \pm 1470)/{\rm RT)s}^{{\rm - 1}} \\ k(2) = 10^{13,05 \pm 0.17} \,\exp (- (33930 \pm \,\,\,590)/{\rm RT)s}^{{\rm - 1}} \\ \end{array} $$\end{document}. Further data are given in Tables 1 and 2.The carbonyl groups of the complex 1 show at 180 K, where the ring inversion process is frozen out, a single line at 211 ppm, i. e. the coalescence temperature of the carbonyl groups must be 〈 180 K.

Notes: Photolysis of Conjugated Epoxy-dienesDirect and sensitized excitation of the (E)-β-ionylidene-epoxides 1 and 4 leads to different types of isomerizations. Thus photocycloelimination to the cyclopropene-ketones 2 and 6 is only achieved by 1(π, π*)-excitation (λ=254 nm), whereas 3(π, π*)-excitation (λ 〉 280 nm, acetone) gives selective C(1′), O-cleavage of the oxirane (1→7 - 10 and 4→11 - 13). In contrast to 1 the twofold methylsubstituted epoxy-diene 4 shows mainly (E/Z)-isomerization (4 → 5) on both 1(π, π*)- and 3(π, π*)-excitation while the isomerizations 4→6 and 4→11 - 13 are minor processes, only.

Notes: Synthesis of the Sesquiterpene Ketone Shyobunon and of its DiastereoisomersShyobunon (12) and 6-epishyobunon (13) as well as their epimers 10 and 11 were synthetized in five steps from geranyl- (1) and nerylsenecionate (2), respectively. Ester enolate rearrangement [5] of 1 and 2 furnished the key intermediates 3 and 4 in high yield and in about 80% stereoselectivity [6] (Scheme 1). Conversion of the acid mixture 3/4 to the cyclohexanone derivatives 7 and 8 succeeded in 35-40% yield by means of cyclization of their acidchlorides with tin tetrachloride to the mixture of 5 and 6, followed by HCl elimination with diazabicyclononene (DBN) (Scheme 2). Selective reduction of 7 to 10 and 11, and 8 to 12 and 13 with triphenyltinhydride completed the synthesis.The relative configuration of 10 and 11 as well as of 12 and 13 were deduced from the 13C-NMR. spectra (Scheme 4, Table 2). The structure of ‘epishyobunone’ is revised: it has the structure 13, and not 11 as described earlier [1]. This is discussed in connection with the rearrangement of acoragermacrone (16) [18] to shyobunone (12) and 6-epishyobunone (13) (Scheme 5).

Notes: The reaction of 4,6-dinitroisophthalaldehyde and 4,6-dinitroisophthalonitrile with pyridine4, 6-Dinitroisophthalaldehyde (4) gives on reaction with pyridine 4,6-diformyl-3-(1′-pyridinio)-1-phenolate (5), whereas 4,6-dinitroisophthalonitrile (7) gives under the same conditions one main product: 3-(1′)-pyridinio-4, 6-dicyano-1-phenolate (10) and two side products: 2-(1′-pyridinio)-4, 6-dicyano-3-nitro-1-phenolate (11) and 4, 6-dicyano-3-nitro-1-phenol (12). The new structures were elucidated by 1H-NMR. and 13C-NMR. spectroscopy.

Notes: Syntheses of Moniliformin, a Mycotoxine with a Cyclobutenedione StructureSix different routes to 3-hydroxy-3-cyclobutene-1, 2-dione (4), the free acid of the mycotoxine Moniliformin (=alkali salt of 4) are described. A common feature of all pathways is the synthesis of cyclobutanes having the oxidation level 6. Moniliformin precursors which are easily transformed to 4 by acid catalysed hydrolysis include [2+2]-cycloadducts of ketene with tetraalkoxy-olefins, 3,4,4-trialkoxycyclobutenes, derivatives of polyfluorinated cyclobutenes, the brominated [2+2]-cycloadduct of ethyl vinyl ether and dichloroketene, tetrabromocyclobutanone, [2+2]-photocycloadducts of dichlorovinylenecarbonate with dichloroethylenes, and the dimer of chloroketene. The most convenient synthesis via the [2+2]-cycloadduct of tetraethoxyethylene and ketene (14b) is reported in detail and produces 4 in four simple steps in 57% overall yield. In addition, two new syntheses of squaric acid (56) are described.

Notes: Glycine in aqueous solutions of trimetaphosphate or linear polyphosphate at pH adjusted to 8.1-9.0, is condensed at room temperature to diglycine and very small amounts of triglycine. The addition of imidazole increases the yield of triglycine by a factor of almost 10; supplementary addition of magnesium ion does not increase this effect. On the contrary to what has been observed at pH 11.5-12.0, the addition of sodium cyanide or cyanamide at pH 8.1-9.0 diminishes strongly the yield of triglycine and to a lesser degree that of diglycine. The prebiotic significance of the condensation of amino acids in aqueous solutions of polyphosphates in the presence of imidazole is discussed.

Notes: Dye-sensitized photooxygenations of 3 pairs of (E)/(Z) trisubstituted olefins were studied in order to establish the partitioning between the 3 possible ene additions. The (E)-isomers underwent only the 2 ene additions (〉95%) involving H-atom abstractions at the same, disubstituted side of the olefins, termed syn ene additions, with almost equal ease. The (Z)-isomers underwent mainly (85-90%) the syn ene additions, with the ones leading to the tertiary hydroperoxides distinctly favoured, and some (10-15%)ene additions at the monosubstituted side of the olefin, termed anti ene addition.

Notes: The radical anions of [2.2.2.2]paracyclophane- 1,9,17,25-tetraene (I), [2] (2, 5)-furano [2]paracyclo [2] (2,5)furano [2]paracyclophane-1,8, 16,23-tetraene (II), [2]-(2,5)thiopheno [2]paracyclo [2] (2,5)thiopheno [2]paracyclophane-1,8,16,23-tetraene (III) and [2.2.2.2](2,5)thiophenophane-1,8,15,22-tetraene (IV) have been studied by ESR. and ENDOR. spectroscopy. The assignment of the proton coupling constants, aHμ is to a large extent based on investigations of deuteriated derivatives. These investigations impressively demonstrate the potential of ENDOR. spectroscopy as an analytical tool. The Arrhenius activation energies, Ea, for the rotation of phenylene fragments about the bonds linking them with the ethylenic parts in I⊖ and II⊖ are 36±6 and 28±4 kJ/mol, respectively. The value aHμ of the olefinic protons in I⊖ appears substantially smaller than expected for the corresponding planar radical anion. The hyperfine data for II⊖, III⊖ and IV⊖ are consistent with the conformations which should minimize the deviations of the macrocyclic π-systems from planarity. In the case of II⊖, tight ion pairs are formed by the radical anion and its counter-ion, K⊕, in DME, owing to the strong association of the alkali metal cation with one of the furan moieties. An analogous interaction of K⊕ with a thiophene moiety in III⊖ must be weaker, since no effects of ion pairing on the ESR. and ENDOR. spectra have been observed for this radical anion.

Notes: Absolute Configuration of α-Doradexanthin and of Fritschiellaxanthin, a New Carotenoid from Fritschiella tuberosa IYENG.Fritschiellaxanthin, a new oxocarotenoid produced by the green alga Fritschiella tuberosa, in a nitrogen-deficient medium is now shown to be (3 S, 3′ R, 6′ R)-3, 3′-dihydroxy-β, ∊-caroten-4-one (4b). It is not identical with α-Doradexanthin (5b) previously found in goldfish (Carassius auratus) and to which we assign the (3 S, 3′ S, 6′ R)-chirality. Consequently, fritschiellaxanthin and α-Doradexanthin are C(3′)-epimers of lutein-4-on. Furthermore, the so-called ′lutein′ from goldfish has now been found to be identical with 3′-epilutein (3). Therefore, fritschiellaxanthin is probably biogenetically derived from lutein (2), whereas α-Doradexanthin is formed from 3′-epilutein (3) with 3, O-didehydrolutein (=(3R, 6′R)-3-hydroxy-β, ∊-caroten-3′-one10) as a precursor. For comparison, optically active 10 and 3 have been prepared from lutein (2) and are fully characterised.

Notes: Mikrolin (8) and dechloromikrolin (9) have been shown to exist as tautomeric mixtures in solution. The structures of mono-O-trifluoroacetyl Mikrolin (10) and di-O-acetyl Mikrolin (11) have been elucidated. The products 15 to 23 from reduction of the metabolites 8 9 with Pd/C and Zn in aqueous acetic acid have been identified. The 13C-NMR. spectra of Mikrolin (8) and dechloromikrolin (9) and their derivatives have been completely assigned Based on the results of incorporation experiments with sodium [1-13C]-, [2-13C]- and [1, 2-13C]-acetate, a biosynthetic pathway is proposed for Mikrolin (8).

Notes: Relative rates of the photoreactions of 1-(1), 2-(2) and 4(5)-valerylimidazole (3) as well as the yields of photo-fragmentation product 10 from 1-(7), 2-(8) and 4(5)-stearoylimidazole (9), respectively, were determined. A reaction path via Norrish Type II fragmentation involving the carbonyl group of 1-acylimidazoles was ruled out.

Notes: Conformational factors leading to Type II elimination and to cyclobutanol formation were studied in the irradiation of N-acylimidazoles with simple acyl groups as well as of their photochemical acyl migration products.

Notes: The irradiation of 1-(dehydroabietoyl) imidazole (3) gave no Type II elimination product but yielded instead compounds 6 and 7 by migration of the imidazolylcarbonyl group from C(4′) to C(6′) of the abietan moiety, probably via a cyclobutanol intermediate. Similarly, irradiation of 1-(13′-deisopropyl-10′-epi-dehydro-abietoyl)imidazole (13) gave only a small amount of Type II fragmentation product 20, the main products derived from γ-hydrogen abstraction being the cyclobutanol derivatives 16 and 17.

Notes: (+)-β-Eudesmol (7), (+)-10-epi-elemol (8), (-)-(Z)-dihydrofarnesol (3), and an alcohol believed to be a guai-9-en-11-ol (4) have been isolated from Galbanum resin. Together with (-)-β-dihydroagarofuran (1) and epi-ligulyl oxide (13) (reported naturally occurring for the first time), 10-elemol (8) and 10-epi-junenol (2) involve the enantiomeric stereochemistry at C (10) compared with β-eudesmol 7, and guaiol 5, the major sesquiterpene alcohol of Galbanum.

Notes: Regiospecific addition of benzeneselenenyl bromide to ethyl vinyl ether followed by alcoholysis of the initially formed β-bromoalkyl selenide 1 by primary, secondary or tertiary allylic alcohols 2a-e gave the mixed acetals 3a-e. Subsequent oxidation and thermal treatment of the corresponding selenoxides 4a-e furnished after saponification the γ, δ-unsaturated acids 7a-e in excellent overall yields. The entire sequence (Scheme 2) represents a new version of the ester Claisen rearrangement.

Notes: The complexation kinetics of the two macrocycles 1 and 2 with Co2+, Ni2+, Cu2+ and Zn2+ have been measured by pH-stat techniques. The rates are first order in metal and ligand concentration and depend upon the pH. This results from the different reactivities of the various protonated species of the macrocyclic tetraamines. The resolved rate constants are given in Table 2.In comparison with other 14-membered cyclic aliphatic tetraazasystems 1 and 2 react more slowly with metal ions. This might be a consequence of the more rigid structure induced by the pyridine ring.

Notes: The 12-16 membered tetraazamacrocycles 1-6 were synthesized, their protonation constants and complexation kinetics measured at 25° and I = 0.50. The results of Table 1 Show that pK3H is strongly influenced by the ring size whereas pK2H and pK1H are relatively insensitive to it. This can be understood in terms of electrostatic interactions of the positive charges when located on adjacent amino groups.The kinetics of complex formation between the macrocyclic ligands and several transition metal ions have been studied by pH-stat and stopped-flow techniques and the results have been analyzed as bimolecular reactions between the metal ion and the different protonated species of the ligands. The rate constants, given in Table 2, show that the macrocycles react less rapidly than analogous open chain amines. However, for a given protonated species of the ligand the rate of complexation follows the order Cu2+ 〉 Zn2+ 〉 Co2+ 〉 Ni2+ which parallels the sequence of their water exchange rates. For the diprotonated tetraamines LH22 reacting with Cu2+ the slower rates seem to be mainly a consequence of electrostatic interactions, since a correlation between logkLH2Cu and pK3H exists. For LH+, however, the complexation rates of a metal ion with the different macrocycles are all in one order of magnitude and do not depend in a regular way on the ring size or the basicity of the ligand. It is therefore suggested that in this case other factors such as unfavourable preequilibria must be considered as important.

Notes: Constituents of Osmanthus Absolute, 4th Communication. Megastigma-5, 7 (E), 9-triene-4-one and Megastigma-5, 8 (E)-diene-4-oneIn continuation of our communications on constituents of Osmanthus absolute, we now report on the occurrence of the two title compounds 1 and 2a in this natural substrate (0.01-0.02% each). Their structures were confirmed by synthesis starting from β-ionone via the common intermediate 4-oxo-β-ionol (9). Some further minor components bearing corresponding structural features are tabulated in view of possible biogenetic pathways leading to 1 or 2a, respectively.In order to clarify the olfactory behaviour, we also synthesized some analogous derivatives in the irone series, these substances being not yet found in nature.

Notes: The dinucleoside phosphate ΠdpΠd (4) was synthesized from the monomers 1-(5′-O-monomethoxytrityl - 2′ - deoxy - β - D - ribofuranosyl) - 2 (1 H) - pyridone ((MeOTr) Πd, 2) and 1-(5′-O-phosphoryl-3′-O-acetyl-2′-deoxy-β-D-ribofuranosyl)-(1H)-pyridone (pΠd(Ac), 3). Its 6.4% hyperchromicity and an analysis of the 1H-NMR. spectra indicate that the conformation and the base-base interactions in 4 are similar to those in natural pyrimidine dinucleoside phosphates.

Notes: The photoelectron spectrum of tetrakis (methylidene)cyclobutane (1, ‘[4]radialene’) is reported. The electronic states of 1+ are assigned on the basis of model calculations and with reference to related systems. Jahn-Teller activity in the degenerate states is discussed. A failure of the simple LCBO-model for the π(eg)-orbital of 1 is noted and traced to the fact that this orbital, though having a symmetry-equivalent π*-counterpart, does not interact with it. This feature is confined to [4n]radialenes; their total π-energies are therefore higher than those of the other members. It is shown that radialenes, in principle, do not constitute a class analogous to that of the linear polyenes as inferred earlier.

Notes: The He(Iα) and He(IIα) spectra of tetrafluorobutatriene 3(F) have been recorded for comparison with those of butatriene 3(H). Ab initio double-zeta basis self-consistent field (SCF) and configuration interaction calculations on butatriene show that, contrary to previous assignment, no shake-up band is expected to appear in the 9-10 eV energy range of the photoelectron spectrum. Further, such SCF calculations on tetrafluorobutatriene support the use of the perfluoro effect in assigning the purely π orbital ionizations. It is argued that 3(F) is a key compound for the study of the perfluoro effect. This is supported by a qualitative comparison of its photoelectron-spectroscopic results with those of other perfluoro systems.

Notes: Stationary points of the INDO energy hypersurface for various orientations of ethylene in external electric fields of the strength F=0, 2, 4, 6, 8 and 10 × 1010 V m-1 were found and their characteristics studied by the force constant matrix analysis. Energies, structural parameters, charges, Wiberg indices and dipole moments are presented. The only stable orientation of the ethylene molecule is that for which the C—C bond is parallel to the field direction up to F=6 × 1010 V m-1 (orientation (a) in Fig. 1). Above this value the molecule is structurally unstable and it decomposes to the hydride anion and the C2H3+ cation. Rotational instability was found for two perpendicular orientations of the C—C bond with respect to the field vector, in which the field vector was parallel and perpendicular to the molecular plane. Pseudorotations with negative eigenvalues of force constant matrices lead to the stable orientation (a). No stationary points were found when the angle between the C—C bond and the field vector was between 0 and 90°. The five longest wavelength vibrational bands are presented for selected orientations and field strengths.

Notes: Rearrangements of the Phenylthio Group of Trimethylsilyl-enolethers of α,α-Dialkylated α-Phenylthio-ketonesTrimethylsilyl-enolethers of α,α-dialkylated α-phenylthio-ketones undergo a photochemically induced 1,3-phenylthio shift leading to isomeric enolethers in high yields. The rearrangement can also be carried out under thermal conditions, but the results are less satisfying.

Notes: The octahydroisoindolone moiety related to proxiphomin (1) has been synthesized by condensation of N-benzyloxycarbonyl-protected D, L-phenylalaninal (7) with methyl-(4-methyl-sorbyl)-malonate (11) to yield the branched ethylene derivative 12. Consecutive intramolecular [2+4]-cycloaddition and lactam ring closure of 12 gave the desired octahydroisoindolone derivative 15, possessing adaptable functional groups for the attachment of the macrocyclic ring system.

Notes: Reaction Products from 3-Dimethylamino-2,2-dimethyl-2H-azirine and Phthalohydrazide or Maleohydrazide3-Dimethylamino-2, 2-dimethyl-2H-azirine (1) reacts in dimethylformamide at room temperature with the six-membered cyclic hydrazides 2, 3-dihydrophthalazin-1, 4-dione (2) and 1, 2-dihydropyridazin-3, 6-dione (15) to give the zwitterionic compounds 3 and 16, respectively (Scheme 1 and 7). The mechanism of these reactions is outlined in Scheme 1 for compound 3 (cf. also Scheme 8). The first steps are thought to be similar to the known reactions of 1 with the NH-acidic compounds saccharin and phthalimide (cf. [1]). Instead of ring expansion to the nine-membered heterocycle i (X=CONH, Scheme 8), a proton transfer followed by the loss of water gives 3 (Scheme 1).The structure of the zwitterionic compounds 3 and 16 is deduced from spectral data and the reactions of these compounds (see Schemes 2, 3, 4, 6 and 7). Methylation of 3 yields the iodide 4, which is hydrolysed easily to the 2-imidazolin-5-one derivative 5 (Scheme 2). Hydrolysis of 3 under basic conditions leads to the amide 6, which undergoes cyclization to 7 at 220-230° (Scheme 3). The analogous cyclization has been realized under acidic conditions in the case of 17 (Scheme 7).Catalytic reduction of 3 yields the tertiary amine 14 (Scheme 6), whereas the reduction with sodium borohydride leads to a mixture of 14 and the 2-imidazoline derivative 13. The alcohol 11, corresponding to the amine 14, is obtained by sodium borohydride reduction of the 2-imidazolin-5-one 7 or of the amide 6 (Scheme 3). This remarkably easy reaction of 7 shows the unusual electrophilicity of the lactamcarbonyl group in this compound. The reduction of 6 to 11 is understandable only by neighbouring group participation of N (2′) in the dihydrophthalazine residue.

Notes: Cyclometallation reactions of o-Hydroxy-diarylazocompoundsThe metallation of o-hydroxy-diarylazoligands with Pt(II)- or Pd (II)-salts leads not only to the classical complexes of type 3 but also to coordination compounds of type 2, containing a metal-carbon bond. The latter coordinate carbon monoxide, which can be inserted into the metal-carbon bond, thus leading after reductive elemination of the metal to heterocyclic products.

Notes: Isolation of 1-Allyl-2,3-dimethoxy-4,5-methylenedioxybenzene from Heckeria umbellata (L.) KUNTH (Piperaceae)From the leaves of Heckeria umbellata (L.) KUNTH an oily substance was isolated and its structure deduced. It is 1-allyl-2, 3-dimethoxy-4, 5-methylenedioxybenzene (= Dill-Apiol; 2) and not as previously published 1-allyl-2, 5-dimethoxy-3, 4-methylenedioxybenzene (= Apiol; 1) [2].

Notes: Synthesis of acetylenic alcohols by alkylation of ω-hydroxy-1-alkynesIn liquid ammonia and with lithium amide, the alkylation of an ω-hydroxyl-alkyne proceeds with good yield with primary or secondary alcohols and with fair yield with tertiary alcohols. It is a very convenient way to prepare many substituted acetylenic alcohols.

Notes: Metal reduction of pyrene and of pyrene isomers under carefully controlled conditions yields the corresponding dianions. The properties of the neutral compounds and of the dianions are studied via 1H-NMR. spectroscopy. Whereas the former exhibit similar behaviour, the charge distribution within the dianionic species proves to be very different. As a consequence, some of the polycyclic dianions can be regarded essentially as (4n)π-perimeters, an approach which is satisfactorily rationalized by simple MO-models. Further evidence in favour of this bonding scheme comes from the ESR. spectroscopic measurement of the spin density distribution within the corresponding radical anions.

Notes: Investigation by gas liquid chromatography of a small but organoleptically typical subfraction of Oriental tobacco condensate led to the identification of 47 compounds. Of these 21 have hitherto not been reported as Oriental tobacco constituents, and 14 appear to be novel to all tobacco types. The latter are (E)-3-methyl-non-2-en-4-one (1), (E)-1-(2, 3, 6-trimethylphenyl)-but-2-en-1-one (3), pentadecan-15-olide (12), 8α, 13:9α, 13-diepoxy-15, 16-dinorlabdane (17), (Z)-octadec-9-en-18-olide (18), (E)-2-ethylidene-6, 10, 14-trimethylpentadecanal (21), the norlabdanoids 9, 10, 11, 14, 15, 16, tridecan-2-one, and 2-phenylethyl isovalerate. The macrolides 12 and 18 represent the first musk compounds detected in tobacco. Identification were made by direct comparison (MS. and/or 1 H-NMR./IR.) with the authentic chemicals synthesized whenever necessary.

Notes: Substituted 2, 4, 5-trithiahexanes 1, a class of substances recently found in roasted meat, have been synthesized via two different routes.

Notes: Clark-like Hydrogen DetectorA quantitative hydrogen detector, similar to the Clark oxygen electrode, has been proposed by Green et al. [1] in 1967. Such a detector gives a signal which is directly proportional to the hydrogen partial pressure without consuming any hydrogen itself. We have taken up the proposal of Green et al., and have realized a very sensitive and under many circumstances also a selective detector, which is easy to handle and which can be used in gaseous phase as well as in aqueous solution. Sensitivity of 0.1 Torr or even better can be achieved. The main differences to the Clark electrode are that a platinized platinum electrode has to be used instead of a blank platinum electrode and that a more positive potential has to be applied. We give a detailed description of the construction and the handling of the Clark-like hydrogen detector.

Notes: The purpose of this investigation is to provide synthetic proof for the structure of dogfish (Squalus acanthias) α-MSH and to investigate the consequences of the presence of methionine in position 13 and the lack of the N-terminal acetyl group in this hormone. Because of the facile oxidation of methionine (13) during handling or storage, a number of specifically oxidized hormones (Met4 and Met13) as well as tripeptides belonging to the C-terminal second message sequence were investigated. All the products were prepared by classical methods in homogeneous solution; intermediate and end products were extensively purified and characterized (Tables 3 and 4). The assays for melanotropic activity were performed in vitro with the modified reflectometric assay using the skin of Rana pipiens. It is concluded that the structures assigned to dogfish α-MSH I and II are correct and that the isolated samples contain slight quantities of [13-methionine (S-oxide)]dogfish α-MSH and [4, 13-bis-methionine (S-oxide)]dogfish α-MSH. The peptides with methionine in position 13 are as active in this assay as those containing valine. This also holds for the —NH2/—OH interchange distinguishing dogfish α-MSH I from dogfish α-MSH II. However, the lack of the N-terminal acetyl group strongly reduces the biological activity. Its introduction into dogfish α-MSH I results in a product that is equipotent with mammalian α-MSH. These and other conclusions are discussed in detail.

Notes: Synthesis of 1,3,4-Oxadiazoles and 4,5-Dihydro-l,2,4-triazines from 3-Dimethylamino-2,2-dimethyl-2 Hazirine and Carbohydrazides3-Dimethylamino-2, 2-dimethyl-2 H-azirine (1) reacts with aromatic carbohydrazides to give 2-(1-amino-1-methylethyl)-5-aryl-1, 3, 4-oxadiazoles (7, 10, 11). With ethyl carbazate the azirine 1 forms the aminoester 15, which is easily cyclized to the 4, 5-dihydro-1, 2, 4-triazin-3 (2H)-one 16. From the reaction of 1 with oxamohydrazide (17) and oxalodihydrazide 19 the 4, 5-dihydro-1, 2, 4-triazin-3-carboxamide 18 and the symmetric compound 20, respectively, have been isolated. Reactions supporting the structures of the new compounds are described.

Notes: Constituents of Osmanthus-Absolute, 3rd communication: Derivatives of TheaspiranesFour isomeric new 7-oxo-dihydrotheaspiranes were identified in Osmanthus absolute. Their configuration was proved by synthetic correlations with racemic as well as optically active theaspiranes A and B. These two compounds also occurring in the same natural substrate were first correlated with the (-)-theaspirone A of known absolute configuration and the (+)-theaspirone B, respectively, thus giving the background for all further stereochemical relationship work. In depth studies in the 1H- and 13C-NMR.-spectroscopy field including all possible and now synthetically available hydroxy derivatives of the new oxo compounds enabled us to unambiguously assign structures 1 to 4 to the natural products. Some further constituents bearing the same spirocyclic skeleton were also detected in Osmanthus absolute.

Notes: Disproportionation/combination ratios Pd/Pc of self-reacting t-butyl radicals are determined as a function of solvent and temperature. the observed large solvent and temperature dependences are ascribed to anisotropic reorientational motions of the radicals during their encounter in the solvent cage. Results for other alkyl radicals are compatible with this concept.

Notes: Reaction of 1, 1-dichloro-2, 5-diphenylbenzocyclopropene (10a) with 1 equiv. of silver fluoride yields 1-chloro-1-fluoro-2, 5-diphenylbenzocyclopropene (10c). Both 10a and 10c react with excess silver fluoride to give the difluoro compound 10b. Both 10b and 10c are also prepared via cyclo-additions of 1, 2-dichloro-3, 3-difluorocyclopropene (14) or 1, 2, 3-flurocyclopropene (13) with diphenylbutadiene and subsequent aromatization with base. Similarly. 1-chloro-1-fluorobenzocyclopropene (16) is accessible from butadiene and 13.

Notes: An efficient synthesis of methyl (±)-jasmonate and (Z)-jasmone is described. The Key step is a phase-transfer reaction between cyclopentane (9) and 1, 4-dibromo-2-pentene (6a/b) to give the spiro [2.4]hepten-4-ones 4a and 4b.

Notes: Conversion of the Diastereoisomeric 12-and 6-membered 1-Acetyl-2-methyl-1-cycloalkanols to 1-Ethynyl-2-methyl-1-cycloalkenesThis paper is concerned primarily with a derivation of the E-configuration of 1-ethynyl-2-methyl-1-cyclododecene (10), which plays a role in mechanistic considerations on a method for ring expansion by 3 carbon atoms described in apreceding paper [1]. The derivation is based on an argument using the results of the dehydration of trans-1-acetyl-1-2-methyl-1-cyclododecanol (4) to 10 with phosphorus oxychloride and pyridine. That this dehydration is stereospecific can be concluded from its regiospecificity since the cis-hydroxyketone 3 dehydrates mainly to 1-ethynyl-12-methyl-1-cyclododecene (mixture of stereoisomers 11 and 12). An x-ray analysis shows the indicated configurations of the two hydroxyketones 3 and 4.The direction (anti) of the stereospecificity of the double bond introduction during the 4→10 conversion is deduced from the similarity of the behaviour of the two stereoisomeric 1-acetyl-2-methyl-1-cyclohexanols 8 and 9 under the same conditions and from mechanistic considerations, which make it likeley that the anti-elimination behaviour observed in the 6-membered system has not changed over to a syn-elimination behaviour in the 12-membered system. The configurations of the two 6-membered hydroxyketones 8 and 9 correspond to those of the precursor1-ethynyl-2-methyl-1-cyclohexanols 6 and 7, which were clarified with the help of 13C-NMR.-spectral coupling observations.It is of interest that the hydroxyketones 3, 4, 8 and 9 react with phosphorus oxychloride and pyridine so as to introduce both a double and a triple bond. It is probable that the double bond is introduced first, inasmuch as the triple bond is not introduced in the absence of activation of the hydroxyl group, as for instance in acetylcyclohexane. This can be used as an argument that the conversion of the acetyl to an ethynyl group in 3, 4, 8 and 9 does not affect the stereospecificity of the dehydration which introduces the ring double bond.1-Acetyl-2-methyl-1-cyclododecene (24), a previously isolated compound with pleasant odor, was synthesized by hydration of 10. This furnishes an argument for the E-configuration of 24.

Notes: Partial Synthesis of (20S)-ψ-Vincamine and (20S)-epi-16ψVincamineAn attempt of classification of the indole alkaloids is presented; (20S)-ψ-vincamine. (20S)-16-épi-ψ-vincamine and (20S)-ψ-apo-vincamine have been prepared from catharanthine by partial synthesis.

Notes: High resolution He (Iα) and He (IIα) photoelectron spectra of cubane are reported. The assignments of the bands to different states of the cubane radical cation are made on the basis of ab initio STO-3G and MINDO/3 calculations, using geometries optimized within each treatment. The vibrational fine-structure observed supports the proposed assignment. An open shell MINDO/3 model for ground state cubane radical cation suggests that the Jahn-Teller distorted system fluctuates between twelve equivalent structures of C2v-symmetry. Localized molecular orbitals derived from the STO-3G model of cubane indicate that the major feature which discriminates this molecule with respect to other hydrocarbons is the large interaction matrix element between the opposed CC-σ-orbitals of each face.

Notes: Nitric oxide reacts with phenylethylene and arylalkenes under the action of sunlight and at room temperature giving dimeric nitronitroso compounds prouved by IR. spectroscopy (see Table 2) and the corresponding nitroolefins. The main gaseous product is nitrogen as prouved by gaz liquid chromatography (see Table 1). The dimeric nitronitroso compounds can also be obtained by the reaction of dinitrogen trioxide with olefins. The structure of the nitronitroso compounds was further discussed. They may be reduced to give monoamines corresponding to the nitrogroup and may be also converted into nitroolefins.

Notes: CH-Acidity in α-position to the N-Atom of N, N-Dialkylamides with Sterically Protected Carbonyl Groups Contribution to the Nucleophilic Amino AlkylationSterically protected amides 1 such as the 2,4,6-triisopropyl-benzoic acid derivatives 3, 8b and 10 undergo readily H/Li-exchange with s-butyllithium at the CH3N- or CH2N-groups. The resulting organolithium compounds (cf. 9, 11) are alkylated and hydroxyalkylated with primary haloalkanes, aldehydes, and ketones under chain elongation in the amine position of the amides. The (E/Z)-rotamers of the dialkylamides 7 and 8are separated by chromatography; the amides 4-6, 12, and 13 formally derived from β-hydroxyamines are obtained in the (Z)-form only. The configurational (E/Z)-assignments follow from NMR. and IR. data. The erythro and threo configuration of the two diastereomeric amides 12a and 12b are tentatively concluded from Eu(fod)3-1H-NMR.-shift experiments. The results strongly suggest that the H/Li-exchange takes place regioselectively at the CH—N group which is in cis-position to the C=O double bond (→14). The methyl 2,4,6-tri(t-butyl)benzoate (18) can also be deprotonated to the lithium acyloxymethanide 19 which is trapped by alkylation with 1-iodooctane (→20). - The steric protection of the carbonyl groups in the products 4-8, 10, 12, 13, and 20 prevents their ready hydrolysis to amines and alcohols, respectively. Therefore, triphenylacetic acid derivatives 21 rather than 2,4,6-triisopropylbenzoic acid derivatives for use in the electrophilic substitution of equation (1) are recommended. The trityl group in 21 may be considered a C-leaving-group (C—C protective group, cf. 22, 23). The acetamide 25 reacts readily (→26) and then with electrophiles to give products 27a-c. As shown in the Table, the amides 27 are cleaved under a variety of conditions with formation of triphenylmethane. LiAlH4 produces a tertiary amine, CH3Li a secondary amine, and dissolving alkali metals/naphthalene under aprotic conditions mixtures of secondary amine and its formamide (hydrolysed by acid treatment). Thus the overall process (2) is feasible.

Notes: Starting from the circular dichroism (CD.) of testosterone propionate oriented in a liquid crystal matrix it is shown that the CD., measured with light beams having different directions of propagation with respect to the molecular framework, is different in magnitude and frequency dependence. The vibrational structure is analysed.From the concentration and temperature dependence of the CD. and UV. spectra an order parameter ρ and its concentration and temperature dependence is derived. By this an estimation for the direction of the transition moment of the n → π* transition is given.

Notes: Regiospecific deuteriation of folic acidIntroduction of a nitroso function at the N (10)-position of folic acid activates the C(9)-hydrogen atoms in such a way, that the exchange of H with D at this position, in NaOD-solution, is extremely facilitated. This fact is utilized in the synthesis of 9,9-dideuterio-folic acid (IV), 7,9,9-trideuterio-folic acid (VII) and 7-deuterio-folic acid (IX). These three products are necessary for the 1H-NMR.-spectroscopical determination of the conformation of 5,6,7,8-tetrahydrofolic acid and its derivatives.

Notes: α-Hydroxymethylene Elongated Aldehydes by Partial Reduction of CyanohydrinsAfter acetal-protection of the hydroxy group, a number of cyanohydrins (derived from aldehydes or ketones) were reduced and hydrolysed to afford α-hydroxyaldehydes in good yields. Other synthetically useful reactions of the intermediate α-cyano and α-formyl acetals have also been studied.

Notes: Investigations on the Migratory Aptitude of Allyl Groups in Aliphatic Carbenium-IonsThe acetolysis (80°) of the 4-bromobenzenesulfonates given in Scheme 6 were investigated in regard to determine type allyl/methyl migratory aptitudes in the secondary carbenium ion a (Scheme 24). In all cases olefins (about 80%) and acetates (about 20%) were formed which can be derived from the rearranged tertiary carbenium ions b (being formed by allyl group migration) and c (being formed by methyl group migration).Olefin A and acetate H, originated in carbenium ion a, occurred in the acetolysis mixture only in minor amounts (〈2%). By acetolysis of [l4C]-20, isolation of [14C]-4,5-dimethyl-l, 3-hexadiene ([14C]-45), and degradation of this diene (Scheme 16) it could be shown (4 Scheme 15) that the ions b and c (Scheme 24, R1—R4=H) are not interconverted by a [1,2]-hydride shift (extent 〈 1%). Since olefin D arises by proton loss from ion b as well as from ion c, [14C]-4,5-dimethyl-l,4-hexadiene ([14C]—44≡ D, R1—R4= H) was also degraded (cf. Scheme 15 and Scheme 17). It was found that [14C]-44 contained 48% of the label in the methyl group at C(4) and 52% in the methyl groups at C(5), i.e. 48% of 44 is formed via the allyl migration path and 52% via the methyl migration path. In addition, acetolysis of d3-20 and product analysis showed, that the d3-ally1 moiety migrates as expected only in a [1,2]-fashion. Product analysis of the acetolysis mixtures of erythro- and threo-24 (cf. Scheme 19 and Tables 4 and 5) revealed that carbenium ion a must exist as an intimate ion pair (with the 4-bromobenzenesulfonyloxy-ion) which has lost its configuration at C(1) only partially. This is indicated by reversed ratios (1: 11 and 10: 1, resp.) in the formation of erythro- and threo-2,3,4-trimethyl-l, 5-hexadiene (erythro- and threo-77) arising from ion b (Scheme 24, R1—R3 = H, R4= CH,). The acetolysis of 1,2,2,4-tetramethyl-4-pentenyl4-bromobenzenesulfonate (23) was not studied in detail, but the appearance of a seventh product in the olefin part cannot be explained by the genesis paths in Scheme 24. Thus, it may be concluded that in this case a third tertiary carbenium ion d3 (Scheme 21) is produced by cyclization of a3. Cyclizations of this type are known to occur in carbenium ions bearing β-substituted allyl groups (see Scheme 22). The kinetic data of the acetolysis of all 4-bromobenzenesulfonates (Table 6) are in accord with a rate determining ionization step leading to a since all activation enthalpies resp. entropies are within 25.5 L± 0.6 kcal/mol resp. -0.2 ± 1.7 e.u. The migratory aptitudes given in Table 7 show, that allyl groups migrate only slightly easier than methyl groups in ion a. This is in strong contrast to allyl substituted methylcyclohexadienyl cations (generated in the acid catalyzed dienone/phenol and dienol/benzene rearrange-ment) which undergo exclusively [1,2]-ally1 migrations (Schemes 3-5).

Notes: The syntheses of the bis (styryl)benzenes 4 and 5 and of the aza analogue 3 are described. Diamine 3 and dialdehyde 5 were cyclized to the 14-membered macrocycles 19 and 27, respectively. Diamine 4 and glyoxal give the 28-membered macrocycle 28. The cyclizations are discussed.

Notes: Results of crystal structure analyses of seven 1, 8-disubstituted naphthalenes (2a, 8-(N,N-dimethylamino)-1-naphthyl methyl ketone; 2b, 8-(N, N-dimethylamino)naphthalene-1-carboxylic acid; 2c, methyl 8-(N, N-dimethylamino)naphthalene-1-carboxylate; 2d, 8-methoxy-1-naphthyl methyl ketone; 2e, 8-methoxynaphthalene-1-carboxylic acid; 2f, N, N-dimethyl-8-methoxynaphthalene 1-carboxamide; 2g, N, N-dimethyl-8-hydroxynaphthalene-1-carboxamide) with a nucleophilic centre (N(CH3)2, OCH3, OH) at one of the peri positions and an electrophilic centre (carbonyl C) at the other are described. All seven molecules show a characteristic distortion pattern: the exocyclic bond to the electrophilic centre is splayed outward, and the one to the nucleophilic centre is splayed inward; the carbonyl C is displaced from the plane of its three bonded atoms towards the nucleophile. This distortion pattern differs from that found in other 1,8-disubstituted naphthalenes and is interpreted as an expression of incipient nucleophilic addition to a carbonyl group. The crystal structure of 2b contains an ordered arrangement of equal numbers of amino acid and zwitterionic molecules.