[GRAPHICS]
N-Boc-L-Leucinol was converted to two C-13 side chain precursors of the 9-d
ihydrotaxane analogue ABT-271. The trans-oxazolidine acid 4 and the cis-Boc
-lactam 2b were prepared in 44% and 40% overall yield, respectively, and wi
th excellent (>98%) stereochemical purity.