The selective C-10 acylation of 10-deacetylbaccatin III to baccatin III and derivatives is very efficiently catalysed by lanthanide trifluoromethanesulfonates. Baccatin III, now readily available through this procedure, is an important precursor for an economically viable semisynthesis of paclitaxel and its derivatives. (C) 1998 Elsevier Science Ltd. All rights reserved.