Recoverable chiral sulfoxides for asymmetric synthesis: application to stereoselective carbonyl reduction and the asymmetric synthesis of allylic alcohols
The enantiomerically pure cyclic sulfinamide S(S)R-(+)-3 reacts with the sodium enolates of ketones to give the corresponding homochiral sulfoxides.Reduction of the carbonyl group in these products may be achieved using a variety of reducing agents the best of which were DIBAL-H or DIBAL-H/ZnBr2, which give complementary products of high diastereomeric excess.Reduction of the hydroxy sulfoxides with Raney nickel proceeds in low yield and causes partial racemisation of the products.However the combined use of a durected reduction followed by a facile sulfenic acid elimination provides a synthesis of allylic alcohols in high enentiomeric excess.
Butlin, Roger J.,Linney, Ian D.,Mahon, Mary F.,Tye, Heather,Wills, Martin
p. 95 - 106
(2007/10/03)
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