Asymmetric Benzoin Condensation Catalyzed by Optically Active Thiazolium Salts in Micellar Two-phase Media

Abstract

Three thiazolium salts, 3-[2-(l-3-p-menthyloxy)ethyl]thiazolium bromide (1), 3-(l-3-p-menthyl)thiazolium halides (2), and 3-(l-3-p-menthyl)-4-methylthiazolium perchlorate (3) have been examined for the catalysis of benzoin condensation in micellar two-phase media. The catalytic activities on the chemical yields of benzoin were observed to be high for 1 and 2 but low for 3. On the contrary, for the asymmetric induction, 3 gave much higher optical purity of 35.3% than in the cases of 1 and 2 (0.8–3.5%). These results are discussed in terms of micellar and conformational effects.