A selective intramolecular transacylation of taxoids accompanying with the oxetane ring opening.

A selective intramolecular transacylation from C-4 to C-5 of taxoids, which occurred simultaneously with the oxetane D-ring opening and was promoted by TiCl4, was presented. The optimal condition was found to be treatment of substrates in double dose of dichloromethane (per mg of substrate dissolved in 2 mL DCM) with 1 eq of TiCl4 at 25°C for 10 min.