General and Synthetic Methods: Volume 8 (Specialist Periodical Reports, Band 8) - Hardcover

Hardcover

ISBN 10: 0851868940 ISBN 13: 9780851868943

Verlag: Royal Society of Chemistry, 1986

Inhaltsangabe

Specialist Periodical Reports provide systematic and detailed review coverage of progress in the major areas of chemical research. Written by experts in their specialist fields the series creates a unique service for the active research chemist, supplying regular critical in-depth accounts of progress in particular areas of chemistry. For over 80 years the Royal Society of Chemistry and its predecessor, the Chemical Society, have been publishing reports charting developments in chemistry, which originally took the form of Annual Reports. However, by 1967 the whole spectrum of chemistry could no longer be contained within one volume and the series Specialist Periodical Reports was born. The Annual Reports themselves still existed but were divided into two, and subsequently three, volumes covering Inorganic, Organic and Physical Chemistry. For more general coverage of the highlights in chemistry they remain a 'must'. Since that time the SPR series has altered according to the fluctuating degree of activity in various fields of chemistry. Some titles have remained unchanged, while others have altered their emphasis along with their titles; some have been combined under a new name whereas others have had to be discontinued. The current list of Specialist Periodical Reports can be seen on the inside flap of this volume.

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A series of reviews by leading specialists in their fields which gives systematic and comprehensive coverage of the progress in major areas of research.

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General and Synthetic Methods Volume 8

A Review of the Literature Published During 1983

By G. Pattenden

The Royal Society of Chemistry

Copyright © 1986 The Royal Society of Chemistry
All rights reserved.

ISBN: 978-0-85186-894-3

Contents

Chapter 1 Saturated and Unsaturated Hydrocarbons By J. M. Clough and C. R. A. Godfrey, 1, 
Chapter 2 Aldehydes and Ketones By S. C. Eyley, 84, 
Chapter 3 Carboxylic Acids and Derivatives By D. W. Knight, 131, 
Chapter 4 Alcohols, Halogeno-compounds, and Ethers By L. M. Harwood, 200, 
Chapter 5 Amines, Nitriles, and Other Nitrogen-containing Functional Groups By S. G. Lister, 245, 
Chapter 6 Organometallics in Synthesis, 312, 
Chapter 7 Saturated Carbocyclic Ring Synthesis By T. V. Lee, 381, 
Chapter 8 Saturated Heterocyclic Ring Synthesis By K. Cooper and P. J. Whittle, 407, 
Chapter 9 Highlights in Total Synthesis of Natural Products By K. E. B. Parkes and G. Pattenden, 497, 
Reviews on General and Synthetic Methods By G. Pattenden and G. M. Robertson, 541, 
Author Index, 548, 

CHAPTER 1

Saturated and Unsaturated Hydrocarbons

BY J. M. CLOUGH AND C. R. A. GODFREY

1 Saturated Hydrocarbons

Many new methods for the preparation of alkanes via reductive removal of functional groups have been reported during the year. A preparatively useful method for the conversion of carboxylic acids into alkanes has been developed by Barton and his co-workers. Primary, secondary, and tertiary carboxylic esters (1) derived from thiohydroxamic acids such as N-hydroxypyridine-2-thione undergo efficient radical chain decarboxylation to the corresponding nor-alkanes on treatment with either tri-n-butyltin hydride or t-butylmercaptan. Under these mild reaction conditions, ketones, olefins, and normal carboxylic esters remain unchanged. Decarboxylation of carboxylic acids can also be effected using sodium persulphate and a catalytic amount of silver nitrate. Unstabilized alkyl radicals from aliphatic acids afford alkanes or, in the presence of copper(II) salts, alkenes. By contrast, arylacetic acids give benzylic radicals, and these dimerize to give 1,2-diarylethanes in moderate yields.

Williams and Moore have reported that the reduction of a variety of heterocyclic thiones to the corresponding methylene compounds occurs readily on heating with an excess of tri-n-butyltin hydride and a radical initiator (e.g. Scheme 1). Conversion of the cyclic thiocarbonate (2) into the 1,3-dioxolane (3) is noteworthy in that the Corey–Winter reaction does not take place under the reaction onditions. The desulphurization of thiols and thioketones to alkanes and alkenes using sodium triethylborohydride and iron(II) chloride is improved by adsorption of the borohydride onto alumina. Moreover, this heterogeneous reaction occurs at room temperature and products are easily isolated by simple filtration. A variety of benzylic di- and tri-arylmethyl mercaptans react with stoicheiometric amounts of [Fe3(CO)12] or [Co2(CO)8] under phase-transfer conditions to give the corresponding hydrocarbons in good yields.

Monosubstituted thiiranes are reduced to alkanes on treatment with Raney nickel in ethanol at –40°C, conditions under which olefinic bonds are unaffected.

On irradiation, solutions of diselena[3.3]cyclophanes in HMPA are transformed cleanly into the corresponding cyclophanes (e.g. Scheme 2).

Treatment of (hydroxymethyl)diphenylphosphine oxides (4) with P2I4 in carbon disulphide at room temperature affords excellent yields of the alkyldiphenylphosphine oxides (5) with no trace of the corresponding iodides.

Suzuki and his co-workers have shown that benzyl alcohols are smoothly deoxygenated on treatment with P2I4 in boiling benzene. The reaction works well even with sterically hindered secondary benzyl alcohols, as illustrated in Scheme 3. Extending this work, the same group has reported that a mixture of LiAlH4 and P2I4 offers a mild alternative to conventional methods for the deoxy-genation of aromatic ketones (e.g. Scheme 4). Halogens, esters, and olefinic bonds are not affected by these reaction conditions.

Ueno and his co-workers have described conditions under which tosylates, including those derived from primary alcohols, undergo efficient radical deoxy-genation to give hydrocarbons. A noteworthy example is the selective removal of the tosyl group from the diol derivative (6) which takes place without the need to protect the free hydroxy-group.

Several reports describing the use of lithium triethylborohydride for the reduction of alkyl halides, especially alkyl fluorides, have been published during the year. Catalytic amounts of silver perchlorate markedly accelerate the reduction of 1,1-dibromocyclopropanes to the corresponding monobromides by LiAlH4. This catalyst also facilitates the reduction of tertiary or sterically hindered alkyl bromides which are normally resistant to LiAlH4. gem-Bromochloro-cyclopropanes react with a mixture of diethyl phosphonate and triethylamine to give the corresponding chlorocyclopropanes exclusively, and (trichloromethyl)-benzene is reduced to (dichloromethyl) benzene in a yield of 86% under the same conditions. Photostimulated reduction of either cyclohexyl chloride or bromide with LiAlH4 in the presence of di-t-butyl peroxide gives cyclohexane in good yield. Vinyl bromides are converted into olefins under these conditions, but yields are only moderate. α-Halogenocarbonyl compounds are smoothly dehalogenated on treatment with sodium hydrogen telluride, generated in situ from tellurium and NaBH4 in ethanol.

α-Nitrohydrazones (7), readily prepared from the corresponding nitroalcohols (8), are cleanly reduced to the hydrazones (9) on treatment with LiAlH4. However, the reaction fails for nitrohydrazones (7) in which R2 and R3 are both hydrogen atoms.

Dimeric products often encountered during the reduction of nitroalkenes to the corresponding nitroalkanes with NaBH4 can be avoided by carrying out the reaction at 25°C in the presence of silica gel, in a mixture of chloroform and propan-2-ol. Reasonable yields of alkanes can be obtained by electrohydrogenation of both alkenes and alkynes using a nickel-plated cathode coated with Raney nickel powder. However, many other functional groups are also reduced under these conditions.

Alper and Heveling have reported the first examples of organometallic phase-transfer catalysis under acidic conditions. For example, hydrogenation of 9,9'-bifluorenylidene (10) or diarylethylenes occurs on treatment with [Co2(CO)8] or [Co2(CO)6(PBu3)2] and tetrafluoroboric acid under phase-transfer conditions. Anthracene, however, is not reduced. The solvated ion pair [(C8H17)3NMe]+[RhCl4]- catalyses the hydrogenation of a variety ofonsaturated compouds under phase-transfer conditions. Even aromatic substrates may be reduced to the corresponding alkanes at room temperature and under a pressure of 2 atm of hydrogen, but reaction rates are sensitive to steric effects.

Reactive halides such as benzyl bromide undergo homo-coupling on treatment with titanocene methylene–zinc halide complexes of the type [Cp2TiCH2.ZnX2](X=Cl or I).

Reetz and Westermann have reported that treatment of lithium alkoxides of the type (11) with a 1:1 mixture of MeTiCl3 and Me2TiCl2 at –40°C affords the methylated products (12), which are potentially useful as synthetic tetra-hydrocannabinoid intermediates. Undesirable Wagner–Meerwein rearrangements or...

Details zur Ausgabe

• Verlag: Royal Society of Chemistry
• Erscheinungsdatum: 1986
• Sprache: Englisch
• ISBN 10: 0851868940
• ISBN 13: 9780851868943
• Einband: Gebundene Ausgabe
• Anzahl der Seiten: 584
• Herausgeber: Pattenden G.
• Kontakt zum Hersteller: Nicht verfügbar
• Verantwortliche Person: gpsr@libri.de; gpsr@libri.de; ; Friedensallee 273; Hamburg; 22763; Deutschland