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  • 1
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Diastereoselective Thermal or Acid-catalyzed Rearrangement of N,N′-Dibenzylidene-1,2-cyclopropanediamines to cis-2,3-Diaryl-2,3-dihydro-1H-1,4-diazepinesThe trans-N,N′-dibenzylidene-1,2-cyclopropanediamines t1a-g and t6a,b are obtained in the reaction of the trans-1,2-cyclopropanediamines t4 and t5, respectively, with aromatic aldehydes. In contrast, only the cis-N,N′-disalicylidene-1,2-cyclopropanediamines c1b and c6b can be isolated when the aromatic aldehydes are allowed to react with the cis-1,2-cyclopropanediamines c4 and c5, respectively. In the other cases, the intermediate cis-bisimines isomerize in situ to yield the cis-2,3-diaryl-2,3-dihydro-1H-1,4-diazepines c3a-d and 7a, respectively. In [D5]bromobenzene solution, the isolated bisimines t1a, c-e, g and c6b, t6a rearrange above 90°C to give the corresponding dihydrodiazepines c3a, c-e, g and 7a, b, in the neat, molten state above 120°C. Surprisingly, in acetate-buffered methanol solution the dihydrodiazepines c3a, d, are also formed in the reaction of trans-1,2-cyclopropanediammonium bromide (t4 · 2 HBr) with aldehydes at temperatures as low as 20°C. The diastereoselective step of these isomerizations, i. e. the Cope rearrangement of the cis-bisimines c1 and c6, is fast even at 20°C. The cis-bisimines c1 and c6 arise via a thermal or acid-catalyzed trans cis diastereomerization when the sequence starts from trans-1,2-cyclopropanediamine derivatives. All 2,3-diaryl-2,3-dihydrodiazepines which were obtained through rearrangement possess exclusively the cis configuration as shown by comparision with the authentic pair of diastereomers c3a, t3a and by 1H NMR spectroscopy. The 1H NMR spectra of the cis-2,3-dihydrodiazepinium cations c3 · H⊕ in trifuoroacetic acid indicate slow ring inversion up to 20-25°C. The free enthalpies of activation for the diastereotopomerization of 2-H and 3-H of the cis- 1,4,6-D3]-2,3-dihydrodiazepinium cations in [D]trifluoroacetic acid range from Δ G≠361≈ 60 (for c3b) to Δ G≠361 = 75.5 kJ/mol (for c3g). Besides slow ring inversion, teh free base c3g as well as the cation c3g · H⊕ exhibit slow rotation of the 2,4,6-trimethylphenyl groups at C3 and C3.
    Notes: Aus den trans-1,2-Cyclopropandiaminen t4 und t5 und aromatischen Aldehyden erhält man die trans-N,N′-Dibenzyliden-1,2-cyclopropandiamine t1a-g bzw. 16a,b. Dagegen lassen sich bei der Umsetzung aromatischer Aldehyde mit den cis-1,2-Cyclopropandiaminen c4 und c5 nur die cis-N,N′-Disalicyliden-1,2-cyclopropandiamine c1b bzw. c6b isolieren. In den anderen Fällen isomerisieren sich die intermediären cis-Bisimine in situ zu den cis-2,3-Diaryl-2,3-dihydro-1H-1,4-diazepinen c3a-d bzw. 7a. Die isolierten Bisimine t1a,c-e,g und c6b, t6a lassen sich in [D5]Brombenzol erst bei 90°C, in der Schmelze oberhalb 120°C, in die entsprechenden Dihydrodiazepine c3a,c-e,g bzw. 7a,b umlagern. Überraschenderweise entstehen in Acetat-gepuffertem Methanol die Dihydrodiazepine c3a, d auch aus dem trans-1,2-Cyclopropandiammoniumbromid (t4 · 2HBr) und Aldehyd, und zwar schon bei 20°C. Der diastereoselektive Schritt dieser Isomerisierungen ist eine schon bei 20°C rasche Cope-Umlagerung der cis-Bisimine c1 und c6. Diese entstehen durch thermische oder bei 20°C säurekatalysierte trans → cis-Diastereomerisierung, wenn man von trans-1,2-Cyclopropandiamin-Derivaten ausgeht. Alle durch Umlagerung erhaltenen 2,3-Diaryl-2,3-dihydro-1H-1,4-diazepine besitzen cis-Konfiguration, was durch Vergleich mit dem authentischen Diastereomerenpaar c3a, t3a und 1H-NMR-spektroskopisch bewiesen wurde. Die 1H-NMR-Spektren der cis-2,3-Dihydrodiazepinium-Kationen c3·H⊕ in Trifluoressigsäure zeigen noch bei 20-25°C langsame Ringinversion an. Die Freien Aktivierungsenthalpien der Diastereotopomerisierung von 2-H und 3-H der cis-[1,4,6-D3]-2,3-Dihydrodiazepiniumkationen in [D]Trifluoressigsäure betragen ΔG313≠ ≈ 60 (c3b bis ΔG≠361 = 75.5 kJ/mol (c3g). Die freie Base c3g und das Kation c3g · H⊕ zeigen neben langsamer Ringinversion auch noch langsame Rotation der beiden 2,4,6-Trimethylphenylgruppen an C2 und C3.
    Additional Material: 2 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1003-1012 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions with Isocyanides. - Synthesis of Dark-blue Dyes from 1,4-Quinones and Aryl Isocyanides1,4-Benzoquinone reacts with aryl isocyanides 2a-d in boiling toluene or xylene forming darkblue 1:2 and 1:4 adducts, the 4,7-isoindolediones 3a-d and the 1,5- and 1,7-bis(arylamino)-benzodipyrrolediones 4a-c and 5a-c, respectively, which can be separated by chromatography. The structure of the 4-methylphenyl isocyanide adducts 3b, 4b, and 5b is established by NMR spectroscopy. The 1:2 adduct 3b reacts with two moles of 4-methylphenyl isocyanide (2b) affording the isomeric 1:4 adducts 4b and 5b. However, in a similar reaction with 4-chlorophenyl isocyanide (2c) surprisingly only the 1,5-bis(arylamino) derivative 8 is isolated. 1,4-Naphthoquinone (10) reacts with 4-methylphenyl (2b or 4-nitrophenyl isocyanide (2d) to yield the 4,9-benzo[f]isoindoles 11b and d, respectively.
    Notes: 1,4-Benzochinon reagiert mit den Arylisocyaniden 2a-d in siedendem Toluol oder Xylol zu tiefblauen 1:2- und 1:4-Addukten, den 4,7-Isoindoldionen 3a-d bzw. den 1,5- und 1,7-Bis(arylamino)benzodipyrroldionen 4a-c und 5a-c, die chromatographisch getrennt werden. Die Struktur der (4-Methylphenyl)isocyanid-Addukte 3b, 4b und 5b wird NMR-spektroskopisch bewiesen. Das 1:2-Addukt 3b ergibt mit zwei Molen (4-Methylphenyl)isocyanid (2b) die isomeren 1:4-Addukte 4b und 5b; mit (4-Chlorphenyl)isocyanid (2c) wird jedoch überraschenderweise nur das 1,5-Bis(arylamino) Derivat 8 isoliert. 1,4-Naphthochinon (10) bildet mit (4-Methylphenyl)-(2b) bzw. (4-Nitrophenyl)isocyanid (2d) die 4,9-Benzo[f]isoindoldione 11b und d.
    Additional Material: 1 Ill.
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  • 3
    ISSN: 0170-2041
    Keywords: 1,2-Cyclopropanedicarboxylates ; Curtius degradation ; Carbamic acid esters ; Urethanes ; 1,2-Cyclopropanediamines ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclopropanediamines, 4. - Synthesis and 1H-NMR Spectra of Pure Diastereomers of 1,2-Cyclopropanediamines and 1,2-Cyclopropanediammonium DibromidesThe efficient preparation of pure diastereomers of N,N′-(1,2-cyclopropanediyl)diurethanes 16-18 and -diammonium dibromides 4, 19, and 20 is reported. Curtius rearrangement of cis- and trans-1,2-cyclopropandicarboxylic dihydrazides 14 yields di(O-benzyl) diurethanes 16 on a 10-100 g scale. The cis-1,2-cyclopropanedicarboxylic dihydrazides cis-14 tend to form bicyclic products. Thus, from cis-14a a small amount of 22a is obtained besides the diurethane cis-16a. Cyclisation is the main reaction in the case of cis-1,2-dimethyl-1,2-cyclopropanedicarboxylic hydrazide (cis-14e) which affords the bicyclic products 22e and 24, but no diurethane. The 1,2-dimethyl-1,2-cyclopropanedicarboxylic acid (27) reacts with diphenyl phosphorazidate to produce the monobenzyl ester 29. The diurethanes 16 are methylated (→ 17) and benzylated (→ 18) at both nitrogen atoms. The benzyloxycarbonyl group is removed from the diurethanes 16-18 by the action of hydrogen bromide in acetic acid to yield the 1,2-cyclopropanediammonium dibromides 4, 19, and 20. The 1H-NMR spectra are analysed and the results are employed as criteria for the configurations.
    Additional Material: 9 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1983 (1983), S. 1230-1236 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Thermal Rearrangements and Nucleophilic Ring cleavage of cis-2,3-Dihydro-2,3-Diphenyl-1H-1,4-diazepinesThermolysis of cis-2,3-dihydro-2,3-diphenyl-1H-1,4-diazepine (c2a) at 150°C in [D5]bromobenzene solution affords quantitatively 2,3-diphenylpyridine (4a) via ring contraction and loss of one mole of ammonia. In striking contrast, on heating a [D5]bromobenzene solution of cis-2,3-dihydro-2,3,6-triphenyl-1H-1,4-diazepine (c2b) to 140°C loss of C7H8 occurs resulting in the formation of 2,5-diphenylpyrimidine (5b) in 70% yield. Mechanisms are proposed in order to rationalize these surprising ring contractions. Piperdine in methanol cleaved the ring of c2a ·H⊕ producing meso-1,2-diphenyl-1,2-ethanediamine (12) and 1,3-dipiperidinopropenylium perchlorate (13).
    Notes: Die Thermolyse von cis-2,3-Dihydro-2,3-diphenyl-1H-1,4-diazepin (c2a) bei 150°C in [D5]Brombenzol ergibt unter Ringkontraktion und Abspaltung von ammoniak quantitativ 2,3-Diphenylpyridin (4a). Dagegen entsteht aus cis-2,3-Dihydro-2,3,6-triphenyl-1H-1,4-diazepin (c2b) bei 140°C in [D5]Brombenzol unter Verlust von C7H8 2,5-Diphenylpyrimidin (5b) in 70% Ausbeute. Für diese überraschenden Ringkontraktionen werden Mechanismen vorgeschlagen. Durch Piperidin in Methanol wird c2a ·H⊕ in meso-1,2-Diphenyl-1,2-ethandiamin (12) und 1,3-Dipiperidinopropenylium-perchlorat (13) gespalten.
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  • 5
    ISSN: 0170-2041
    Keywords: 1,2-Cyclopropanedicarboxylates, cis- and trans- ; Cyclopropanation, large-scale Bonavent-McCoy-Payne cyclopropanation of α,β-unsaturated esters ; cis-trans Separation through distillation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cyclopropanediamines, 3. - Pure Diastereomers of 1,2-Cyclopropanedicarboxylic Acids and DerivativesEfficient preparations of pure diastereomers of dimethyl 1,2-cyclopropanedicarboxylates 2, dicarboxylic acids 3, dicarbonyl dichlorides 4, and dihydrazides 5 are reported. Mixtures of diastereomers of dimethyl dicarboxylates 2a, b, d, e are obtained from α,β-unsaturated methyl carboxylates 7 and methyl α-chlorocarboxylates 8 as well as from 7c, d and the sulfur ylide 10 (2c, d). The diastereomers are separated by fractionating distillations (2a, b, c, e) or crystallization (2d) on a 100-g to 1-kg scale (d.e. ≥ 99%). Only low yields of 2c are obtained in the reaction of methyl crotonate (7c) with methyl α-chloroacetate (8a), since 7c predominantly dimerizes to afford 12. The diesters 2 are converted into the pure diastereomeric diacids 3, dicarbonyl dichlorides 4, and dihydrazides 5. 3,3-Dimethyl-cis-1,2-cyclopropanedicarboxylic acid (cis-3f) is obtained by trans→cis isomerization of trans-3f with the help of acetic anhydride and sodium acetate as catalyst. The configurations of 2-6 and 12 are confirmed by 1H-NMR spectroscopy. Derivatives of cis-1,2-dimethyl-1,2-cyclopropanedicarboxylic acid tend to form bicyclic products. Thus, the reaction of cis-3e with phosphorus pentachloride yields mainly the cyclic anhydride 6e and only small amounts of the dicarbonyl dichloride cis-4e. Furthermore, the dihydrazide cis-5e slowly cyclizes in the solid state to give the N-aminoimide 13 and hydrazine, a reaction which is fast in solution. Pure 13 is obtained by thermolysis of cis-5e at 60-65°C under high vacuum.
    Notes: Durch Umsetzung von α,β-ungesättigten Estern 7 mit α-Chlorcarbonsäureestern 8 werden die 1,2-Cyclopropandicarbonsäureester 2a, b, d, e erhalten. Aus den α,β-ungesättigten Estern 7c, d und dem Schwefelylid 10 entstehen die 1,2-Cyclopropandicarbon-säureester 2c, d. Die Ester werden durch fraktionierende Destillation (2a, b, c, e) oder Kristallisation (2d) in 100-g- bis 1-kg-Mengen diastereomerenrein erhalten. Crotonsäure-methylester (7c) reagiert nur langsam mit 8a zu 2d, vorwiegend aber mit sich selbst zu 12. Aus den Diestern 2 werden einige Disäuren 3, Dichloride 4 und Dihydrazide 5 diasereomerenrein gewonnen. Durch trans→cis-Isomerisierung von trans-3f mit Acetanhydrid unter Natriumacetat-Katalyse wird die 3,3-Dimethyl-cis-1,2-cyclopropandicarbonsäure (cis-3f) hergestellt. H-NMR-Spektren beweisen die Konfiguration der Verbindungen 2-6 und 12. cis-1,2-Dimethyl-1,2-cyclopropandicarbonsäure-Derivate neigen zum Ringschluß. So entsteht aus der Disäure cis-3e mit Phosphorpentachlorid vorwiegend das cyclische Anhydrid 6e neben wenig Dichlorid cis-4e. Das Dihydrazid cis-5e spaltet im festen Zustand langsam, in Lösung rasch Hydrazin ab und cyclisiert zu 13, das durch Erhitzen von cis-5e auf 60-65°C im Hochvakuum rein erhalten wird.
    Additional Material: 5 Tab.
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