AN ENANTIOSELECTIVE, STEREODIVERGENT APPROACH TO ANTI-ALPHA-HYDROXY-BETA-AMINO 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 synt hesised in protected form and high enantiomeric purity from readily av ailable N-Boc-1-tert-butyldimethylsilyl-3-amino-1,2-diols. The prepara tion of the anti series is straightforward, and takes place by protect ion of the secondary hydroxyl group (1-ethoxyethyl) followed by desily lation/oxidation of the primary hydroxyl group, For the preparation of the syn isomers, the secondary alcohol is inverted at the beginning o f the sequence by Mitsunobu methodology (p-nitrobenzoate). Starting fr om homochiral tyldimethylsilyl-3-amino-3-phenylpropane-1,2-diol, the r eady for coupling Taxotere(R) side chain has been prepared in enantiom erically pure form.