General and Synthetic Methods: Volume 11 (Specialist Periodical Reports, 11) - Hardcover

Hardcover

ISBN 10: 0851869246 ISBN 13: 9780851869247

Verlag: Royal Society of Chemistry, 1989

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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 11

A Review of the Literature Published in 1986

By G. Pattenden

The Royal Society of Chemistry

Copyright © 1989 The Royal Society of Chemistry
All rights reserved.

ISBN: 978-0-85186-924-7

Contents

Chapter 1 Saturated and Unsaturated Hydrocarbons By By N. Simpkins, 1, 
Chapter 2 Aldehydes and Ketones By K.E.B. Parkes, 43, 
Chapter 3 Carboxylic Acids and Derivatives By D.W. Knight, 89, 
Chapter 4 Alcohols, Halogeno-compounds, and Ethers By L.M. Harwood, 208, 
Chapter 5 Amines, Nitriles, and Other Nitrogen-containing Functional Groups By C.M. Marson, 262, 
Chapter 6 Organometallics in Synthesis By S.E. Thomas and T. Gallagher, 393, 
Chapter 7 Saturated Carbocyclic Ring Synthesis By T.V. Lee, 518, 
Chapter 8 Saturated Heterocyclic Ring Synthesis By K. Cooper and P.J. Whittle, 547, 
Chapter 9 Highlights in Total Synthesis of Natural Products By K. Carr, D.J. Coveney, and G. Pattenden, 612, 
Reviews on General and Synthetic Methods Compiled by K. Carr, D.J. Coveney, and G. Pattenden, 659, 
Author Index, 668, 

CHAPTER 1

Saturated and Unsaturated Hydrocarbons

BY N. SIMPKINS

1 Saturated Hydrocarbons

A new radical method for the deoxygenation of secondary alchols has appeared. The method consists of first reacting the alcohol with 2,2'-dibenzothiazolydisulphide in the presence of Bu 3P leading to the corresponding sulphide derivative (1), which is then reacted with Bu3SnH to give the hydrocarbon product in excel lent yield (Scheme 1).

A wide variety of aryl aldehydes and ketones can be deoxygenated by a mixture of ZnI2 and NaCNBH3 in dichloroethane. The reagent also gives good results with benzylic, allylic and tertiary alcohols, although attempted reduction of α,β-unsaturated ketones gave complex mixtures of products. Highly efficient conjugate reduction of α,β-unsaturated ketones and aldehydes is possible by use of a three component system comprising a palladium catalyst, a hydrosilane, and zinc chloride (Scheme 2). The same task of conjugate reduction can be accomplished on unsaturated esters, usually in near quantitative yield, using magnesium in methanol.

2 Olefinic Hydrocarbons

The protonolysis of alkenyldialkylboranes to give Z-alkenes can be conducted, in most cases, under neutral conditions-using methanol. More hindered alkenyldisiamylboranes react less well, unless a small amount of a carboxylic acid is added. A variety of Z-alkenyl pheromones was prepared using this method. The synthesis of trans-alkenes and unsymmetrical ketones was also accomplished using vinylic organoborane chemistry.

Cross-coupling reactions are now possible between aryl (or vinyl) halides and trialkylboranes by the use of catalytic palladium (Scheme 3). The reaction appears not to suffer from side reactions due to β-hydride elimination which are normally observed in such processes. The reduction of allylic acetates to the corresponding alkenes has been reported using SmI2 with a Pd(0) catalyst. The reaction gave high yields of deoxygenated products; unfortunately, mixtures of regioisomers usually result.

Brandsma has illustrated the use of a new and highly potent basic mixture comprising ButOK, BuLi and TMEDA, by efficient generation of vinylpotassium from ethene.

Warren's examination of the Horner-Wittig reaction continues with two more papers detailing the stereoselective reduction of α-R2PO - ketones. The phosphorane (2) is normally rather unreactive: however addition of NaH produces the ylide anion (3) which reacts with aldehydes to give predominantly Z-products (Scheme 4).

The homologation of esters via a DIBAL reduction and phosphonate extension sequence is a commonly desired transformation. The DIBAL reduction to give an aldehyde suitable for homologation is often plagued by over-reaction problems, so that a reduction-reoxidation procedure is often required. These problems can be overcome by the neat trick of carrying out the ester reduction in the presence of the phosphonate anion. The Seyferth-Wittig reagent often gives vinylated by-products (4), as well as the usually desired allylsilanes (5) (Scheme 5). Efficient and stereoselective formation of the syn-vinylated product (4) can be promoted by choice of suitable groups on silicon. Wittig-type olefination reactions can be carried out using tungsten alkylidene complexes, and by the use of in situ generated chloromethyl lithium (Scheme 6).

Diiodo alkenes have been prepared via a Wittig-like reaction which requires no base. Me3SiCl accelerates the reaction of both catalytic and stoichiometric copper reagents with unsaturated carbonyl compounds to give the desired silylenol ethers.

An extensive study of the Co2(Co)8-catalysed reaction of acetates and lactones with CO and HSiEt2Me has appeared. This reaction constitutes a very general, mild and high-yielding synthesis of siloxymethylidene products (Scheme 7).

Vinyl sulphides are available by reaction of phenylthiocarbenes with nitrile anions. Yields on the whole are fair to good, and with some modification several intramolecular versions are possible (Scheme 8). Vinyl sulphides, vinyl selenides and ketene seleno(thio) acetals are formed in high yield by reaction of an appropriate vinyl bromide or dibromide with PhSe- or PhS- in the presence of a Ni(II) catalyst. β-Phenylthio-nitro-olefins have been prepared as mixtures of stereoisomers as shown in Scheme 9.

Oxidation of the sulphide (6) to either the corresponding sulphoxide or sulphone was also possible, and the products were used in Diels-Alder reactions.

Alkenyl fluorides are available by reaction of the corresponding lithio compound with N-tert-butyl-N-fluoro-benzene sulphonamide (Scheme 10).

Two new reports extend the chemistry of fluorinated vinyl organometal lics. In the first, trifluorovinyl l ithium is shown to be much more stable in Et2O (up to -30°C) than in THF. Remarkably, the other research paper by the same group reports that the corresponding zinc reagent F2C=CF-ZnCl is stable for several days in THF at room temperature. These findings allowed considerable extension to the synthetic repertoire of these reagents. A variety of fluorinated products, including perfluoroalkylated alkenyl iodides are available via a pal ladium-catalysed reaction between perfluoroakyl iodides (RfI) and alkynes. This method and two other routes to alkenyl iodides are outlined in Scheme 11. The use of bis(pyridine)iodotetrafluoroborate (7) in conjunction with various metal salts gave good yields of the desired 1,2-iodofunctionalised olefins. Curran's notable contributions to radical chemistry continue with a novel reaction which isomerises hex-5-ynyl iodides to the product (iodomethylene)cyclo-pentanes.

2,2-Disubstituted vinylsilanes have been prepared in regio and stereoselective fashion by reaction of aryl iodides with alkynyl silanes in the presence of a pal ladium catalyst. This and another pal ladium-catalysed transformation leading to aryl vinysilanes are outlined in Scheme 12. The latter process, involving arylation of trimethylvinylsilane with aryl iodides takes place smoothly if silver sal ts are included in the mixture; otherwise styrenes are formed via a presumed addition-desilylpal ladation. The scope of the palladium mediated addition of silylstannanes to acetylenes highlighted last year has been further examined. Allenes react with bis(phenyldimethylsilyl)cuprate to give either vinylsilanes or al lylsilanes depending on the structure of the al lene (Scheme 13)....

Details zur Ausgabe

• Verlag: Royal Society of Chemistry
• Erscheinungsdatum: 1989
• Sprache: Englisch
• ISBN 10: 0851869246
• ISBN 13: 9780851869247
• Einband: Gebundene Ausgabe
• Anzahl der Seiten: 716
• Herausgeber: Pattenden G.
• Kontakt zum Hersteller: Nicht verfügbar
• Verantwortliche Person: GPSR Kontakt; gpsr@libri.de; ; Friedensallee 273; Hamburg; 22763; Deutschland