Baccatin III was efficiently synthesized from the BC ring system of Ta
xol, 2 alpha,10 beta-dibenzyloxy-11 beta-(t-butyldimethylsiloxy)-7 bet
a-hydroxy-1 alpha-(4-methoxybenzyloxy)-8 thyl-4-methylene-trans-bicycl
o[6.4.0]dodecan-9-one (1), by successive constructions of A and D ring
s via respective intramolecular pinacol coupling and oxetane forming r
eaction.