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Enantioselective Reduction Of Ketones
Enantioselective ketone reductions convert prochiral ketones into chiral, non-racemic alcohols and are used heavily for the synthesis of stereodefined alcohols. Carbonyl reduction, the net addition of H2 across a carbon-oxygen double bond, is an important way to prepare alcohols. Stoichiometric reducing agents to accomplish this task include lithium aluminium hydride, sodium borohydride, alkoxy borohydrides, alkoxy aluminium hydrides, and boranes. Although stoichiometric chiral reducing agents often afford products with high enantioselectivity, the necessity of a stoichiometric amount of chiral material is a disadvantage. The catalytic, asymmetric reduction of ketones may be accomplished through the use of catalytic amounts of an oxazaborolidine catalyst in conjunction with borane or catecholborane as the stoichiometric reducing agent. Oxazaborolidines remain in common use for reductions of simple ketones. Efforts in the field of enantioselective reduction have focused on the devel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithium Aluminium Hydride
Lithium aluminium hydride, commonly abbreviated to LAH, is an inorganic compound with the chemical formula or . It is a white solid, discovered by Finholt, Bond and Schlesinger in 1947. This compound is used as a reducing agent in organic synthesis, especially for the reduction of esters, carboxylic acids, and amides. The solid is dangerously reactive toward water, releasing gaseous hydrogen (H2). Some related derivatives have been discussed for hydrogen storage. Properties, structure, preparation LAH is a colourless solid but commercial samples are usually gray due to contamination. This material can be purified by recrystallization from diethyl ether. Large-scale purifications employ a Soxhlet extractor. Commonly, the impure gray material is used in synthesis, since the impurities are innocuous and can be easily separated from the organic products. The pure powdered material is pyrophoric, but not its large crystals. Some commercial materials contain mineral oil to inhibit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
