General and Synthetic Methods: Volume 9 (Specialist Periodical Reports) - Hardcover

Hardcover

ISBN 10: 0851869041 ISBN 13: 9780851869049

Verlag: Royal Society of Chemistry, 1987

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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 9

A Review of the Literature Published in 1984

By G. Pattenden

The Royal Society of Chemistry

Copyright © 1987 The Royal Society of Chemistry
All rights reserved.

ISBN: 978-0-85186-904-9

Contents

Chapter 1 Saturated and Unsaturated Hydrocarbons By C.R.A. Godfrey, 1, 
Chapter 2 Aldehydes and Ketones By S.C. Eyley, 71, 
Chapter 3 Carboxylic Acids and Derivatives By D.W. Knight, 130, 
Chapter 4 Alcohols, Halogeno-compounds, and Ethers By L.M. Harwood, 233, 
Chapter 5 Amines, Nitriles, and Other Nitrogen-containing Functional Groups By S.G. Lister, 284, 
Chapter 6 Organometallics in Synthesis, 398, 
Chapter 7 Saturated Carbocyclic Ring Synthesis By T.V. Lee, 490, 
Chapter 8 Saturated Heterocyclic Ring Synthesis By K. Cooper and P.J. Whittle, 536, 
Chapter 9 Highlights in Total Synthesis of Natural Products By K.E.B. Parkes and G. Pattenden, 633, 
Reviews on General and Synthetic Methods Compiled by G. Pattenden and G.M. Robertson, 679, 
Author Index, 688, 

CHAPTER 1

Saturated and Unsaturated Hydrocarbons

BY C. R. A. GODFREY

1 Saturated Hydrocarbons

A number of new methods for the preparation of alkanes via reductive removal of functional groups were reported during 1984. All-cis-[5.5.5.5]fenestrane (2), a hydrocarbon containing a four-co-ordinate carbon atom with planoid configuration, has been synthesized by Keese and Luyten. The final step in the synthesis involves an unusual reductive decarboxylation of the lactone (1) on heating to 310 °c under hydrogen in the presence of excess palladium on carbon (Scheme 1). The radical chain decarboxylation of N-hydroxypyridine-2-thione esters reported previously has now been applied to N-protected α-amino-acids and peptides. Under the mild reaction conditions developed for this transformation, indolic, hydroxylic, and phenolic side-chain functions do not require protection (Scheme 2). Furthermore, removal of side-chain carboxy-groups of glutamic and aspartic acid residues appears to be less facile than the α-amino-acid decarboxylation.

Guttierrez and Summerhays have reported on the use of tri-n-butyltin hydride for the selective cleavage of unsymmetrical dialkyl sulphides to the corresponding alkanes and tri-n-butylstannyl alkyl sulphide. A mild, selective procedure for the reductive deselenization of selenides with nickel boride has also been described by Back. The reagent, which is readily prepared by treatment of nickel chloride hexahydrate with sodium borohydride, selectively reduces vinyl and alkyl selenides to the corresponding hydrocarbons, even in the presence of alkenes and sulphides (Scheme 3).

An improved method for the deoxygenation of tertiary alcohols based on the radical chemistry of thiohydroxamic O-esters has been developed by Barton and Crich (Scheme 4). The itermediate mixed oxalate ester (3), formed in situ, undergoes smooth decomposition at 80 °C in the presence of an excess of t-butyl thiol and traces of base to afford the deoxygenated product (4) in 90% yield. The key step in the novel 1-6 oxygen transposition sequence illustrated in Scheme 5 is the selective reduction of the cyclic carbonate (7) to the alcohol (8) using NaBH3CN-[Pd(PPh3)4]-THF. Attempted reduction (LiAlH4-AlCl3) of the intermediate hydroxy-ketone (5) directly to the homoallylic alcohol (8) fails, giving instead the cis-diol (6) with high selectivity.

Khalifa and Rieker have shown that the 3,5-di-t-butyl-1-phenyl-4-oxo-cyclohexa-2, 5-dienyl N-protecting group can be removed electrochemically. Under the reaction conditions, the N-benzyloxycarbonyl group is stable. ortho-Selective dehalogenation of halogenobenzoic acids can be effected with bis(pentafluorophenyl) ytterbium in THF at -78 °C. The reagent is prepared in situ from bis(pentafluorophenyl) mercury and elemental ytterbium. Iida and his co-workers have reported that the use of acetic acid as solvent, both for the preparation and reductive cleavage of steroidal ketone tosylhydrazones, significantly improves yields and reduces unwanted side reactions.

Several examples of asymmetric hydrogenation have appeared during the year. Evans and Morissey have observed dramatic hydroxyl-directed stereochemical control of high-pressure (640 p.s.i.) hydrogenation in both cyclic and acyclic systems when the cationic rhodium complex [Rh(NBD)(DIPHOS-4)]BF4 is used as catalyst. As the examples in Scheme 6 show, excellent selectivity can be achieved even in extremely hindered cases such as in the reduction of the allylic alcohol (9). Homogeneous catalytic hydrogenation of the 3-methylenecyclohexanol (10) in the presence of the complex (11) is highly stereoselective, giving predominantly trans-3-methylcyclohexanol. Reduction of 2-methylenecyclohexanol and 2-methlenecyclohexanemethanol, however, under the same conditions, exhibits poor selectivity. Imamoto and his co-workers have successfully reduced a wide range of unsaturated substrates, including alkynes and alkenes, using the intermetallic hydride LaNi5H6 under nitrogen at atmospheric pressure. The hydride is readily prepared by hydrogenation of LiNi5, which unlike many conventional hydrogenation catalysts is unaffected by substrates containing an amino-group, halogen atom, or thiophene ring. Sodium hypophosphite in the presence of palladium on charcoal has also been examined as a convenient alternative to catalytic low-pressure hydrogenation.

Finally, Baldwin et al. have introduced the use of trityl- and diphenyl-4-pyridylmethyl hydrazones (12) for reductive C-C bond formation from aldehydes and ketones (Scheme 7). Thus, hemolytic decomposition of the intermediate azo-compounds (13) and (14) in the presence of a suitable radical trap, such as ethanethiol, leads to the smooth formation of the corresponding alkanes. Furthermore, on treatment with phosphorus trichloride, the ad ducts (14) are converted into unsymmetrical tri- and tetra-substituted alkenes in moderate yield (24-60%).

2 Olefinic Hydrocarbons

Molecules containing highly strained olefinic bonds continue to be of great theoretical interest. Lenoir and his co-workers, for example, have studied the conformational behaviour of (E)-3, 4-diethyl-2,2,5,5-tetramethylhex-3-ene (15), available in good yield by reductive dimerization of t-butyl ethyl ketone using known methodology (Scheme 8). In an extension of earlier work , Tobe's research group has synthesized a series of bicyclo[n.2.1] bridgehead alkenes of type (16; n=4-6) substituted at the opposite bridgehead position with an acetxy-group. Interestingly, vapour-phase pyrolysis of the alkene (16; n=6) at 400 °c leads via elimination of acetic acid to the novel bicyclo [6.2.1] bridgehead diene (17) in 50% yield. Filipino

The use of low-valent titanium and tungsten for the formation of carbon-carbon bonds is now well established. However, the outcome of the reaction is often unpredictable, depending largely on which method is used for the preparation of the reagent. Reduced tungsten species effective in the reductive dimerization of aromatic carbonyl compounds have now been generated by controlled electroreduction of WCl6 at a platinum electrode. Aliphatic substrates, however, give disappointing results.

General methods for the asymmetric olefination of carbonyl compounds have been scarce in the literature until very recently. Now Hanessian and co-workers have developed the use of chiral bicyclic phosphanamides such as (18) and (19) for this purpose. On deprotonation, these reagents react in a highly...

Details zur Ausgabe

• Verlag: Royal Society of Chemistry
• Erscheinungsdatum: 1987
• Sprache: Englisch
• ISBN 10: 0851869041
• ISBN 13: 9780851869049
• Einband: Gebundene Ausgabe
• Anzahl der Seiten: 736
• Herausgeber: Pattenden G.
• Kontakt zum Hersteller: Nicht verfügbar
• Verantwortliche Person: GPSR Kontakt; gpsr@libri.de; ; Europaallee 1; Bad Hersfeld; 36244; Deutschland