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  • Synthetic methods
  • 1
    Digitale Medien
    Digitale Medien
    Synthesis and Structures of Bis(tetramethylipiperidino)aluminum Halides-X-ray Crystal Structures of tmp2AlX (X = Cl, Br, I) and [tmp2A1(μ-F)l2 (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1047-1052 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Bis(tetramethylipiperidino)aluminum halides ; Alkoxy((tetramethylpiperidino)aluminum halides ; 27Al-NMR spectra ; Aluminum ; Amides ; Synthetic methods ; Bridging ligands ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: N-Lithio-2,2,6,6-tetramethylpiperidine [Li(tmp)] reacts with AlX3 (X = Cl, Br) in diethyl ether/ n-hexane solution to generate the products of substitution and ether cleavage, [tmpAl(X)(μ-OEt)], (la, X = Cl; 1b, X = Br). However, when the reaction is allowed to proceed in n-hexane alone, an almost quantitative yield of compounds tmp2AlX (2a, X = Cl; 2b, X = Br; 2c, X = I) is obtained. According to 27AI-NMR spectroscopy, mass spectroscopy, cryoscopy, and X-ray crystal structure determinations, these compounds are monomeric in the solid state, in solution, and in the gas phase. 2b reacts with AgBF4 yielding the fluoride-bridged dimer (tmp2AlF), 2d, as shown by X-ray crystal structure determination.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19971300805
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  • 2
    Digitale Medien
    Digitale Medien
    Synthesis of 21-(3-Methylbutyl)cholest-5-ene-3β,3′,25-triol and 21-(2-Methylpropoxy)cholest-5-ene-2′,3β,25-triol, the First “Double Side Chain” Cholesterol Analogues (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 1997-2001 
    Details
    ISSN: 0947-3440
    Schlagwort(e): Cholesterol ; Steroid side chain construction ; Alkylations ; Synthetic methods ; Steroids ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The 21-(3-hydroxy-3-methylbutyl)- and 21-(2-hydroxy-2-methylpropoxy)cholestane derivatives 3 and 5, formally double chain hybrid (20R)- and (20S)-cholesterol analogues, were synthesized. The C-22 to C-27 section of the 25-hydroxycholestane side chain was established by stereoselective alkylation with 5-bromo-2-methyl-2-(triethylsilyl)oxypentane of the pregnanoic ester 8, derived from 3β-acetoxyandrost-5-en-17-one (7). Reduction of the ester 9 to the 21-alcohol 10 permitted elaboration of a second hydroxylated side chain, either via the tosylate 11 by alkynation/hydrogenation (yielding intermediate 13) or by alkylation of 10 with bromoacetate (yielding 14) followed by reaction with methyl magnesium bromide.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jlac.199719970928
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  • 3
    Digitale Medien
    Digitale Medien
    Functionalized Ozonides by Substitution Reactions of Chlorinated Ozonides with Difunctional Alcohols (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 2581-2585 
    Details
    ISSN: 0947-3440
    Schlagwort(e): Ozonides, functionalized ; Substitutions ; Alcohols ; Aldehydes ; Synthetic methods ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Substitution of 3-chloro-3,5-bis(chloromethyl)-5-methyl-1,2,4-trioxolane (3) with allyl alcohol gave the corresponding diastereomeric allyloxy-substituted ozonides 4, which were converted into diozonides 7 by ozone treatment. Substitutions of 3 with ethanediol or with 1,3-propanediol gave the corresponding hydroxyalkoxy-substituted ozonides 8, 14, which were oxidized to the corresponding aldehydes 10, 16. Reaction of 3,5-dichloro-3,5-bis(chloromethyl)-1,2,4-trioxolane (1a) with ethanediol gave the corresponding bis(hydroxy)-substituted ozonide 19 as well as a bicyclic ozonide 18 by reaction of 1a with ethanediol in a ratio of 1:1.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jlac.199719971225
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  • 4
    Digitale Medien
    Digitale Medien
    Recent Advances in Organic Synthesis under High Pressure (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 623-635 
    Details
    ISSN: 0947-3440
    Schlagwort(e): High-pressure chemistry ; Nucleophilic aromatic substitution ; Cycloadditions ; Synthetic methods ; Synthesis under neutral, mild conditions ; Supramolecular chemistry ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The most recent successes achieved in organic synthesis by use of high-pressure technique are reviewed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jlac.199719970404
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  • 5
    Digitale Medien
    Digitale Medien
    Synthesis of an Epoxide- and Carbonate-Containing 6-/10-Membered Bicyclodienediyne Analogue of the Neocarzinostaitin Chromophore (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 961-965 
    Details
    ISSN: 0947-3440
    Schlagwort(e): C—C coupling ; Dienediynes ; McMurry reaction ; Neocarzinostatin ; Synthetic methods ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The monocyclo-diendiyne → bicyclo-trienediyne strategy for obtaining dienediyne models of the antitumor antibiotic neocarzinostatin chromophore (1) was extended from generating 6-/11-membered bicyclotrienediynes (e.g. 2 → 4) to generating the 6-/10-membered bicyclotrienediyne 5. In the preparatory steps (Scheme 2), the bistriflate 10 was successively coupled with alkynes 9 and 11. Via the dienediynediol and its subsequent oxidation with the Dess-Martin periodinane, we obtained the monocyclic dienediyne keto aldehyde 13. Cyclization of 13 with low-valent titanium afforded the bicyclotrienediyne 5 in 42% yield (Scheme 3). Compound 5 was converted in five steps - namely ketal cleavage, monosilylation of the resulting diol 14, asymmetric Sharpless epoxidation, desilylation and carbonate formation - into the dienediyne epoxycarbonate 3. The structure of the latter is more closely related to the neocarzinostatin chromophore than our earlier analogues.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jlac.199719970527
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  • 6
    Digitale Medien
    Digitale Medien
    Strategy for the Synthesis of Epoxide- and Carbonate-Containing Dienediyne Models of the Neocarzinostatin Chromophore - Application to the 6-Ring/11-Ring Case[1] (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 947-959 
    Details
    ISSN: 0947-3440
    Schlagwort(e): C-C coupling ; Dienediynes ; Enol triflates ; McMurry reaction ; Neocarzinostatin ; Synthetic methods ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A novel synthetic strategy leading to bicyclic dienediyne models of the chromophore 1 of the anti-tumor antibiotic neocarzinostatin is described. Its key step is a ring-closing McMurry reaction of the dienediyne keto aldehydes 17 or 23. It leads to dienediynediols (compounds 19 and 24, respectively) or to trienediynes (compounds 18 and 25, respectively). Low temperatures favor the formation of dienediynediols while high temperatures favor the formation of trienediynes, so that the McMurry reactions of keto aldehyde 23 show an almost perfect temperature-dependent chemoselectivity (Scheme 6). The trienediyne 25 contains a ketal group which was removed by acid-catalyzed methanolysis (Scheme 8). The resulting diol 31 was mono-tert-butylsilylated to provide the allyl alcohol 36 (Scheme 10). It was epoxidized regio- and stereoselectively with Sharpless' asymmetric epoxidation reagent. The resulting epoxide 37 was converted into the dienediyne epoxycarbonate syn-33 in the final step of a sequence totaling seven steps and 5% yield starting from the bistriflate 3b; 3b itself is accessible from 2-formylcyclohexa none in two steps and 47% overall yield. The dienediyne epoxycarbonate syn-33 is the first synthetic congener of the neocarzinostatin chromophore furnished both with the - correctly configured - epoxide and carbonate rings.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jlac.199719970526
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  • 7
    Digitale Medien
    Digitale Medien
    The Paternò-Büchi Reaction of 3-Heteroatom-Substituted Alkenes as A Stereoselective Entry to Polyfunctional Cyclic and Acyclic MoleculesDedicated to Professor G. A. Olah on the occasion of his 70th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 1627-1634 
    Details
    ISSN: 0947-3440
    Schlagwort(e): Photochemistry ; Synthetic methods ; Oxetanes ; Diols ; Amino alcohols ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The preparation of 3-heteroatom-substituted oxetanes by the Paternò-Büchi reaction, and their application in synthesis are reviewed. 3-Oxetanols and 3-aminooxetanes are the two most important oxetanes in this respect. By tuning the electronic properties of the enol and enamine substrates, a successful photocycloaddition to carbonyl compounds, with high yield, is possible. Since the oxetane formation proceeds stereoselectively, diastereomerically pure products are readily accessible, which can then be used in further transformations. To this end, regioselective ring-opening reactions have been developed, some of which will be discussed in this account.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jlac.199719970803
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  • 8
    Digitale Medien
    Digitale Medien
    Alkenylidenes in Organic Synthesis (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 36 (1997), S. 1164-1170 
    Details
    ISSN: 0570-0833
    Schlagwort(e): carbenes ; carbenoids ; cyclizations ; rearrangements ; synthetic methods ; Carbenes ; Carbenoids ; Cyclization ; Rearrangement ; Synthetic methods ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Alkenylidenes R2C=C: (= alkylidene carbenes) undergo regio- and stereoselective intramolecular C—H insertion reactions that are excellently suited for the synthesis of cyclopentenes. The 1, 2-shifts occurring with R=H and R=Ar are useful for the preparation of alkynes. Alkenylidenes are efficiently generated from carbonyl compounds by diazomethylation, from vinyl halides by α-elimination, from alkynyliodonium salts by addition of nucleophiles, and from alkynes by retro-1, 2-shifts. Specific applications of the various methods, particularly in the synthesis of natural products, are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.199711641
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  • 9
    Digitale Medien
    Digitale Medien
    Regio- and Stereoselective Syntheses with Organocopper ReagentsDedicated to Professor Klaus Hafner on the occasion of his 70th birthday (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 36 (1997), S. 186-204 
    Details
    ISSN: 0570-0833
    Schlagwort(e): chirality ; catalysis ; copper ; reagents ; synthetic methods ; Homogeneous catalysis ; Chirality ; Copper ; Synthetic methods ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Of all of the organometallic reagents currently used to form carbon-carbon bonds, organocopper reagents rank amongst the most important. Interest in these reagents centers not only on their regioselectivity, but also increasingly on their application in stereoselective transformations (principally Michael additions and SN2′ reactions); the use of suitable substrates or chirally modified cuprates can lead to highly diastereo- and enantioselective reactions. Simultaneously, extensions of methods for the preparation and application of these reagents (for example functionalized organocopper species and Lewis acid catalysis, respectively) have opened up new horizons for organocopper reagents. Mechanistically, the reactions are well-documented and understood, but this aspect of the subject has not kept pace with the many rapid developments in preparative chemistry. Organocopper ragents have proved to be indispensable in the synthesis of complex natural products and pharmaceuticals, chiral auxiliaries, and molecules with interesting structural features. In this review we will discuss some of the more recent important developments in this area; the organization will follow the type of selectivity (regio-, diastereo-, and enantioselectivity).
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.199701861
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  • 10
    Digitale Medien
    Digitale Medien
    Homoleptic Metal Carbonyl Cations of the Electron-Rich Metals: Their Generation in Superacid Media Together with Their Spectroscopic and Structural CharacterizationEditorial note: In this review the recommendations of IUPAC Nomenclature have not been followed. The formulas of the neutral coordination compounds have not been enclosed by square brackets in order to distinguish more clearly the neutral compounds from ionic complexes and polyanions. (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 36 (1997), S. 2402-2425 
    Details
    ISSN: 0570-0833
    Schlagwort(e): carbonyl complexes ; cations ; superacidic systems ; synthetic methods ; transition metals ; Carbonyl ligands ; Cations ; Superacidic systems ; Synthetic methods ; Transition metals ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Homoleptic carbonyl cations of the electron-rich metals in Groups 8 through 12 are the newest members of the large family of transition metal carbonyls. They can be distinguished from typical metal carbonyl complexes in several respects. Their synthesis entails carbonylation of metal salts in such superacids as fluorosulfuric acid and “magic acid” HSO3F—SbF5. Thermally stable salts with [Sb2F11]- as counterion are obtained with antimony pentafluoride as reaction medium. Both the [Sb2F11]- anion and superacid reaction media have previously found little application in the organometallic chemistry of d-block elements. Also unprecedented in metal carbonyl chemistry are the coordination geometries with coordination numbers 4 (square-planar coordination) and 2 (linear coordination) for the cation. Formal oxidation states of the metals, and the charges of the complex cations, extend from + 1 to +3: thus CO is largely σ-bonded to the metal, and the CO bond is strongly polarized. Minimal metal → CO π-backbonding and a positive partial charge on carbon are manifested in long M—C bonds, short C—O bonds, high frequencies for C—O stretching vibrations (up to 2300 cm-1), and small 13C NMR chemical shifts (up to δc, = 121). Prominent examples of these unusual homoleptic carbonyl cations, which were recently the subject of a Highlight in this journal, include the first carbonyl cation of a p-block metal [Hg(CO)2]2+, the first trivalent carbonyl cation [Ir(CO)6]3+, and the first multiply charged carbonyl cation of a 3d metal [Fe(CO)6]2+. In this overview we propose to (a) outline the historical origins of cationic metal carbonyls and their methods of synthesis; (b) present a summary of the general field of carbonyl cations, which has developed over a yery short period of time; (c) discuss the structural and spectroscopic characteritics of metal-CO bonding; (d) discuss the special significance associated with reaction media and the [Sb2F11]- anion; and (e) point to the most recent results and anticipated future developments.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.199724021
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  • 11
    Digitale Medien
    Digitale Medien
    Atom Economy - A Challenge for Organic Synthesis: Homogeneous Catalysis Leads the Way (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 34 (1995), S. 259-281 
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    ISSN: 0570-0833
    Schlagwort(e): carbon-carbon coupling ; catalysis ; cycloadditions ; synthetic methods ; C-C coupling ; Atom economy ; Homogeneous catalysis ; Synthetic methods ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Enhancing the efficiency of the synthesis of complex organic products constitutes one of the most exciting challenges to the synthetic chemist. Increasing the catalogue of reactions that are simple additions or that minimize waste production is the necessary first step. Transition metal complexes, which can be tunable both electronically and sterically by varying the metal and/or ligands, are a focal point for such invention. Except for catalytic hydrogenation, such methods have been rare in complex synthesis and virtually unknown for C—C bond formation until the advent of cross-coupling reactions. These complexes may orchestrate a variety of C—C bond-forming processes, important for creation of the basic skeleton of the organic structure. Their ability to insert into C—H bonds primes a number of different types of additions to relatively nonpolar π-electron systems. Besides imparting selectivity, they make feasible reactions that uncatalyzed were previously unknown. The ability of these complexes to preorganize π-electron systems serves as the basis both of simple additions usually accompanied by subsequent hydrogen shifts and of cycloadditions. The ability to generate “reactive” intermediates under mild conditions also provides prospects for new types of C—C bond-forming reactions. While the examples reveal a diverse array of successes, the opportunities for new invention are vast and largely untapped.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.199502591
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  • 12
    Digitale Medien
    Digitale Medien
    Enzymes in Organic Synthesis: Application to the Problems of Carbohydrate Recognition (Part 1)Part 2: Angew. Chem. 1995, 107, Nr. 5; Angew. Chem. 1995, 34, No. 5. (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 34 (1995), S. 412-432 
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    ISSN: 0570-0833
    Schlagwort(e): carbohydrates ; enzymes ; organic synthesis ; Synthetic methods ; Enzymes ; Carbohydrates ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Carbohydrates on cell surfaces are information molecules. Although only seven or eight monosaccharides are commonly used as building blocks in mammalian systems, the multifunctionality of these monomers can lead to the assembly of an immense variety of complex structures. Millions of different tetrasaccharide structures, for example, can be constructed from this small number of building blocks, if branching, the stereochemistry of glycosidic linkages, and the modification of hydroxyl and amino groups are taken into consideration. Oligosaccharides therefore represent an effective class of biomolecules that code for a vast amount of information required in various biological recognition processes, such as intercellular communication, signal transduction, cell adhesion, infection, cell differentiation, development and metastasis. The pace of development of pharmaceuticals based on carbohydrates has, however, been slower than that based on other classes of biomolecules. Part of the reason is the lack of technologies for the study of complex carbohydrates. There is no method to amplify oligosaccharides for sequence analysis. There is no machine available for automated synthesis of oligosaccharides. In addition, the possibly poor bioavailability and difficulties in the large-scale synthesis of carbohydrates have undoubtedly contributed to this slow pace. The enzymatic and chemoenzymatic methods, especially those based on aldolases and glycosyltransferases, described here appear to be useful for the synthesis of mono- and oligosaccaharides and related molecules. Further advances in glycobiology will probably lead to the development of new technologies for the study of carbohydrate recognition and for the synthesis of bioactive carbohydrates and mimetics to control the recognition processes.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.199504121
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  • 13
    Digitale Medien
    Digitale Medien
    Enzymes in Organic Synthesis: Application to the Problems of Carbohydrate Recognition (Part 2)Part 1: Angew. Chem. 1995, 107, 453; Angew. Chem. Int. Ed. Engl. 1995, 34, 412. The numbering of the sections, references, schemes, and Tables follows on from Part 1. (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 34 (1995), S. 521-546 
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    ISSN: 0570-0833
    Schlagwort(e): carbohydrates ; enzymes ; organic synthesis ; Synthetic methods ; Enzymes ; Carbohydrates ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Recognition of carbohydrates by proteins and nucleic acids is highly specific, but the dissociation constants are relatively high (generally in the mM to high μM range) because of the lack of hydrophobic groups in the carbohydrates. The high specificity of this weak binding often comes from many hydrogen bonds and the coordination of metal ions as bridge between sugars and receptors. Though weak hydrophobic interactions between sugars and proteins have also been identified, the unique shape of a complex carbohydrate under the influence of anomeric and exo anomeric effects (the glycosidic torsion angles are therefore often not flexible but are typically somewhat restricted) and the topographic orientation of the hydroxyl and charged groups contribute most significantly to the recognition process. Studies on the structure-function relationship of a complex carbohydrate therefore require deliberate manipulation of its shape and functional groups, and synthesis of oligosaccharide analogs from modified monosaccharides is often useful to address the problem. The availability of various monosaccharides and their analogs for the synthesis of complex carbohydrates together with the information resulting from structural studies (such a NMR or X-ray studies on sugar-protein complexes) will certainly provide a basic understanding of complex carbohydrate recognition. An ultimate goal is to develop simple and easy-to-make non-carbohydrate molecules that resemble the active structure involved in carbohydrate-receptor interaction or the transition-state of an enzyme-catalyzed transformation (for example, glycosidase or glycosyltransferase reactions) and have the approprite bioavailability to be used to control the carbohydrate function in a specific manner. In part one of this review we described various enzymatic approaches to the synthesis of monosaccharides, analogs, and related structures. We describe in this part enzymatic and chemoenzymatic approaches to the synthesis of oligosaccarides and analogs, including those involved in E-selectin recognition, and strategies to inhibit glycosidases and glycosyltransferases.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.199505211
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  • 14
    Digitale Medien
    Digitale Medien
    Fine Feathers Make Fine Birds: The Heck Reaction in Modern GarbDedicated to Professor Wolfgang Lüttke on the occasion of his 75th birthday (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 33 (1995), S. 2379-2411 
    Details
    ISSN: 0570-0833
    Schlagwort(e): C-C coupling ; Synthetic methods ; Heck reaction ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The palladium-catalyzed coupling of haloarenes and haloalkenes with alkenes, which was discovered by Richard F. Heck in the late sixties, has been a topic of fluctuating interest; however, in the last six years activity in this area has flourished. Careful choice of substrates and skillful tailoring of reaction conditions lead to impressive sequences consisting of even different reaction types that occur not only in a consecutive mode, but also in a single operation. The wellestablished Heck reaction, together with other mechanistically related palladiumcatalyzed transformations with arene, alkene, and alkyne derivatives, opens the door to a tremendous variety of elegant and highly convergent routes to structurally complex molecules. The reaction is not disturbed by heteroatoms such as oxygen and nitrogen (nor by sulfur and phosphorus with some limitations). The spectrum of recent achievements starts with a range of chemoselective and regioselective monocouplings of highly functionalized substrates with unsymmetrical and multisubstituted reaction partners. Other advances include cascade reactions in which three, four, five, and even eight new C—C bonds are formed to yield oligofunctional and oligocyclic products with impressive molecular complexity. Even the enantioselective construction of complex natural products with quaternary stereocenters has been achieved with Heck reactions in key steps, as exemplified by the synthesis of crinan, picrotoxinin, and morphine. Today, the Heck reaction is indispensible in the arsenal of synthetic methods available to organic chemists. Certainly it is only a matter of time before the Heck reaction is applied in industrial syntheses.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.199423791
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  • 15
    Digitale Medien
    Digitale Medien
    Synthetic Aspects of Metal-Catalyzed Oxidations of Amines and Related Reactions (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 34 (1995), S. 2443-2465 
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    ISSN: 0570-0833
    Schlagwort(e): catalysis ; oxidations ; synthetic methods ; Amines ; Homogeneous catalysis ; Oxidation ; Synthetic methods ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The metabolism of amines is governed by a variety of enzymes such as amine oxidase, flavoenzyme, and cytochrome P-450. A wide variety of compounds are produced such as ammonia and alkaloids in selective and clean oxidation reactions that proceed under mild reaction conditions. Simulation of the functions of these enzymes with simple transition metal complex catalysts may lead to the discovery of biomimetic, catalytic oxidations of amines and related compounds. Indeed, metal complex catalyzed oxidations have been found to proceed with high efficiency. The first section of this review discusses the dehydrogenative oxidations of amines with transition metal catalysts by transition metal catalysts that simulate amine oxidase. The second section highlights the catalytic oxidation of secondary amines to nitrones by simulation of flavoenzymes. The third section describes the simulation of the function of cytochrome P-450 with lowvalent ruthenium complexes and peroxides. Biomimetic ruthenium-catalyzed oxidations of tertiary amines, secondary amines, and other substrates such as amides, β-lactams, nitriles, alcohols, alkenes, ketones, and even nonactivated hydrocarbons can be performed selectively under mild conditions. These three general approaches provide highly useful strategies for synthesis of fine chemicals and biologically active compounds such as alkaloids, amino acids, and β-lactams.
    Zusätzliches Material: 8 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.199524431
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  • 16
    Digitale Medien
    Digitale Medien
    Ring Closures with Carbon Monoxide (1966)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 5 (1966), S. 435-446 
    Details
    ISSN: 0570-0833
    Schlagwort(e): C-C coupling ; Ring closure ; Synthetic methods ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Carbon monoxide undergoes catalytic reactions with unsaturated compounds to give heterocyclic carbonyl compounds. This cyclization has led to new syntheses of imides, lactams, lactones, phthalimidines, indazolones, and tetrahydroquinazolines.
    Zusätzliches Material: 8 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196604351
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  • 17
    Digitale Medien
    Digitale Medien
    Syntheses of Thiocarboxamides (1966)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 5 (1966), S. 447-461 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Thiocarboxamides ; Synthetic methods ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Methods for the preparation of thiocarboxamides are described with special reference to progress achieved in the last few years. The discussion is arranged according to the eight most important reaction types.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196604471
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  • 18
    Digitale Medien
    Digitale Medien
    Synthesis of Isocyanates and Carbodiimides (1966)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 5 (1966), S. 704-712 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Isocyanates ; Carbodiimides ; Synthetic methods ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of 1,3-disubstituted ureas and 1-arylsulfonyl-3-alkylureas with phosgene permits the preparation of a number of isocyanates and sulfonyl isocyanates that had not previously been described, or that were difficult to prepare. 1,3-Disubstituted thioureas and 1-aryl-(or alkyl)sulfonyl-3-alkylthioureas give carbodiimides. Thionyl chloride and phosphorus pentachloride react with the urea derivatives in the same way as phosgene. Oxalyl chloride reacts with ureas to form parabanic acid derivatives, whereas with thiourea it gives 2-imino-1,3-thiazolidine-4,5-diones, which can isomerize to parabanic acid derivatives.
    Zusätzliches Material: 9 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196607041
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  • 19
    Digitale Medien
    Digitale Medien
    Syntheses of Carboxylic Acids from 1, 1-DichloroehyleneK. Bott, Angew. Chem. 77, 967 (1965); Angew. Chem. internat. Edit. 4, 956 (1965); Chem. Ber., in press.Dedicated to Professor F. Broich on his 60th birthday (1966)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 5 (1966), S. 870-874 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Carboxylic acids ; 1,1-Dichloroethylene ; Synthetic methods ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Many β-alkyl- and β-arylpropionic acids are readily obtainable by the reaction of secondary or tertiary alcohols, esters of these, or olefins with the inexpensive 1, 1-dichloroethylene in sulfuric acid. The success of the synthesis depends on the bulk and energy of the carbonium ion intermediate formed from the alcohols or olefins. With carbonium ions having one H atom attached to the carbonium C atom, electrophilic substitution of the 1,1-dichloroethylene takes place to a small extent. Dicarboxylic acids and carboxylic acids with higher molecular weights are sometimes formed as a result of side reactions.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196608701
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