Optically active (4S,5R)-dihydroisoxazoles 5a–c (90–91% ee) have been prepared by reaction of the epoxyketones 4a–c with hydroxylamine. Reduction of compounds 5a and 5b using lithium aluminium hydride took place exclusively from the Re face to give (1R,2S,3S)-1,3-disubstituted-3-aminopropane-1,2-diols 6a and 6b. These amino-diols were characterised by N-acetylation and the stereochemical sense of the hydride reduction was confirmed by conversion of amides 7a and 7b into α-amino acid derivatives 10a and 10b.

Epoxidation of chalcone (1), using basic hydrogen peroxide, catalysed by polypeptides with defined primary structures demonstrates that the residues in the chain near to the N-terminus determine the stereochemical outcome of the reaction.