Influnce des interactions de torsion dans la reduction des cetones par les hydrures interpretation generale du deroulement sterique de la reduction des cetones acycliques et de l'addition des organomagnesiens sur les aldehydes acycliques

Chérest, M.; Prudent, N.

doi:10.1016/s0040-4020(01)83128-8

Cited by 29 publications

(2 citation statements)

References 52 publications

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“…This compares with a maximum selectivity of 4.9: 1 in the hydride reduction of (3). 8 The homologue 4-phenylpent-4-en-2-01 (4) was prepared from 1-phenylethenylcopper (RLi, Et,O; then CuI, epoxypropane, --80 to 0 "C). This was found to be hydrogenated smoothly and quantitatively to a mixture of (R*,S*)-( 5) and (R*,R*)-( 5) under all conditions tried, the stereochemical outcome being strongly dependent on the catalyst.…”

Section: Thfmentioning

confidence: 99%

Chelate control in the rhodium-catalysed homogeneous hydrogenation of chiral allylic and homoallylic alcohols

Brown¹,

Naik²

1982

J. Chem. Soc., Chem. Commun.

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Section: Thfmentioning

confidence: 99%

Chelate control in the rhodium-catalysed homogeneous hydrogenation of chiral allylic and homoallylic alcohols

Brown¹,

Naik²

1982

J. Chem. Soc., Chem. Commun.

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“…Alternatively, the planar phenyl substituent might be smaller than the methyl group in this particular addition reaction. Although Ph is larger than cyclohexyl in the reduction of PhMeCHCOR and (C 6 H 11 )MeCHCOR, a flat phenyl group is smaller than a cyclohexyl group in some aldol reactions …”

mentioning

confidence: 99%

Stereocontrol in the EtAlCl₂-Induced Cyclization of Chiral γ,δ-Unsaturated Methyl Ketones To Form Cyclopentanones

2003

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EtAlCl(2)-induced cyclization of chiral gamma,delta-unsaturated ketones 11c and 17b takes place mainly from the expected face. The selectivity is modest for 11c (60:40) in which the large substituent is a primary alkyl group and the medium substituent is a methyl group and excellent for 17b (93:7) in which the large substituent is a cyclohexyl group and the medium substituent is a methyl group. The cyclization of 17a is anomalous, suggesting that the phenyl group has more than a simple steric effect.

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Reductions by Metal Alkoxyaluminum Hydrides

Málek

1985

Organic Reactions

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Since the discovery of the reducing properties of diborane (1939), alkali metal borohydrides (1943), and alkali metal aluminohydrides (1946) by H. I. Schlesinger, H. C. Brown, W. G. Brown, and co‐workers, considerable effort has been expended to enhance the versatility and selectivity of these widely used hydride reagents. Whereas diborane exhibits medium reaction large differences exist between sodium borohydride and lithium aluminum hydride. In contrast to the reducing action of sodium borohydride, limited originally to aldehydes, ketones, and acid chlorides, lithium aluminum hydride readily attacks almost all reducible groups. The first progress in bridging this gap in reactivity can be traced to the availability of reagents that are easily prepared by addition of Lewis acids such as boron and aluminum halides to sodium borohydride and lithium aluminum hydride; in this manner diborane, chloroaluminum hydrides, and aluminum hydride have been made accessible as reducing agents. Parallel development led to sodium alkoxyborohydrides with generally higher reactivity than the parent hydride and to alkoxyaluminum hydrides, with markedly lower reactivity and increased chemoselectivity. On the other hand, the reducing capability of sodium borohydride and lithium aluminum hydride has been enhanced by the use of metal salt–hydride systems. A large number of other complex metal hydrides have gained importance as selective reducing agents: lithium aluminum hydride–nitrogen base complexes, sodium cyanoborohydride, lithium cyanoborohydride, sulfurated sodium borohydride, zinc borohydride, diisobutylaluminum hydride, alkylaluminum compounds such as triisobutylaluminum, and tri‐ n ‐butyltin hydride. Sterically hindered organoboranes such as lithium tri‐ sec ‐butylborohydride (L‐Selectride) exhibit excellent selectivity in reduction reactions. High asymmetric induction can be achieved with some chiral organoboranes. Lithium triethylborohydride (Super‐Hydride) is a selective and exceptionally powerful reducing agent. These complex metal hydrides often provide better regio‐ and stereoselectivities than those achieved with alkoxy‐substituted hydrides; nevertheless, the alkoxyhydrides are readily available and continue to be widely used as reducing agents. The purpose of this chapter is to present a critical review of reductions of the following compounds by metal alkoxyaluminum hydrides, alkoxyaluminum hydrides, and chiral metal alkoxyaluminohydride complexes: hydrocarbons, peroxides, ozonides, halogen compounds, unsaturated alcohols, aromatic alcohols, ethers, 1,2‐oxides, aldehydes, ketones, quinones, acetals, and ketals. The literature is covered through December 1981. Important papers that appeared through September 1982 are also reviewed. Some reactions relating to other than reducing properties of these hydrides are included for completeness. The emphasis is on the scope, limitations, and synthetic utility of the hydrides in reduction reactions and on the optimum conditions for their application as reducing agents. Currently accepted views of reaction mechanisms are discussed. Comparisons with reductions by other complex metal hydrides are limited to the most important transformations of the functional groups.

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Influnce des interactions de torsion dans la reduction des cetones par les hydrures interpretation generale du deroulement sterique de la reduction des cetones acycliques et de l'addition des organomagnesiens sur les aldehydes acycliques

Cited by 29 publications

References 52 publications

Chelate control in the rhodium-catalysed homogeneous hydrogenation of chiral allylic and homoallylic alcohols

Chelate control in the rhodium-catalysed homogeneous hydrogenation of chiral allylic and homoallylic alcohols

Stereocontrol in the EtAlCl₂-Induced Cyclization of Chiral γ,δ-Unsaturated Methyl Ketones To Form Cyclopentanones

Reductions by Metal Alkoxyaluminum Hydrides

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Influnce des interactions de torsion dans la reduction des cetones par les hydrures interpretation generale du deroulement sterique de la reduction des cetones acycliques et de l'addition des organomagnesiens sur les aldehydes acycliques

Cited by 29 publications

References 52 publications

Chelate control in the rhodium-catalysed homogeneous hydrogenation of chiral allylic and homoallylic alcohols

Chelate control in the rhodium-catalysed homogeneous hydrogenation of chiral allylic and homoallylic alcohols

Stereocontrol in the EtAlCl2-Induced Cyclization of Chiral γ,δ-Unsaturated Methyl Ketones To Form Cyclopentanones

Reductions by Metal Alkoxyaluminum Hydrides

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Stereocontrol in the EtAlCl₂-Induced Cyclization of Chiral γ,δ-Unsaturated Methyl Ketones To Form Cyclopentanones