Synthesis and Crystal Studies of Novel C(10) Modified Taxanes from 1-Deoxybaccatin VI

Abstract

Two novel taxoids were synthesized from 1-deoxybacctin VI (5) and their crystal structures were determined by X-ray crystallographic techniques. The influence of C(10) substituents of the cyclooctane ring B on molecular conformations were investigated. A larger effect on the conformation of the diterpenoid core is observed when the hydroxyl group is oxidized at the C(9) position and the hydroxyl group is acylated at the C(10) position compared to other baccatin analogs. Compounds 12a and 12c crystallize in the orthorhombic space group P212121. In the structures, the six-membered A ring exhibits a 1, 4-di-planar conformation, the eight-membered B ring adopts boat–chair conformation, and the six-membered C ring exhibits a slightly distorted half-chair conformation. Two novel C-10 modified taxanes from 1-deoxybaccatin VI were synthesized, in which the crystal structure of the two compounds (12a and 12c) were characterized.