Highly stereoselective syntheses of syn- and anti-1,2-amino alcohols

The reduction of N-protected amino ketones can be carried stereoselectively to produce either the syn- or anti-amino alcohol diastereomer. Carbamate-protected amino ketones can be reduced predictably and selectively to anti-amino alcohols with LiAlH(O-t-BU)(3) in ethanol at -78 degreesC. N-Trityl-protected amino ketones can be reduced selectively to syn-amino alcohols with LiAlH(O-t-Bu)(3) in THF at -5 degreesC.