An enantioselective, stereodivergent approach to anti- and syn-alpha-hydroxy-beta-amino acids from anti-3-amino-1,2-diols. Synthesis of the ready for coupling Taxotere(R) side chain

Both anti- and syn-alpha-hydroxy-beta-amino acids are efficiently synthesised in protected form and high enantiomeric purity from readily available anti-N-Boc-1-tert-butyldimethylsilyl-3-amino-1,2-diols. The preparation of the anti series is straightforward, and takes place by protection of the secondary hydroxyl group (1-ethoxyethyl) followed by desilylation/oxidation of the primary hydroxyl group, For the preparation of the syn isomers, the secondary alcohol is inverted at the beginning of the sequence by Mitsunobu methodology (p-nitrobenzoate). Starting from homochiral (2S,3S)-N-Boc-1-tert-butyldimethylsilyl-3-amino-3-phenylpropane-1,2-diol, the ready for coupling Taxotere(R) side chain has been prepared in enantiomerically pure form.