Synthesis and structure of titanium alkoxide complexes with bulky ligands derived from natural products: Asymmetric epoxidation of cinnamyl alcohol

A family of titanium(IV) alkoxide compounds [{Ti(OPri)3(OR)}2], [{Ti(OPri)2(OR)2}2], and Ti(OR)4 (1–12) have been prepared using two different routes: by metathesis reaction of TiCl(OPri)3 and TiCl2(OPri)2 with ROH in the presence of Et3N and alternatively by alcohol exchange of Ti(OPri)4 and the corresponding higher boiling alcohol (ROH=adamantanol, 1,2:3,4-di-O-isopropylidene-α-d-galactopyranose, 1,2:5,6-di-O-isopropylidene-α-d-glucofuranose, 1R,2S,5R-(−)-menthol). These tetra alkoxide titanium(IV) compounds have been characterized by spectroscopic techniques. In addition, some of these chiral Lewis acid titanium compounds, derived from diacetone galactose and diacetone glucose, have been studied in the asymmetric epoxidation of cinnamyl alcohol in order to evaluate their catalytic activity and stereoselectivity.