Studies On Asymmetric Trifluoromethylation Of Aldehydes Catalyzed By Combinatorial Catalysts

The physiological activity of many compounds owning may be further improved by the introduction of fluorine containing alkyl groups, especially the trifluoromethyl group. And experiments also sugguset that trifluoromethyl compounds as the physiologically active medicine or pesticide have a great potential. Thus, trifluoromethylation reaction has been paid much attention in organo fluorine chemistry as well as organic chemistry.The author employed combinatorial method to catalyze the trifluoromethylation reacton of aldehydes using chiral sodium salts and chiral quaternary ammonium salts derived from quinidine. By screening the catalysts, additives and optimizing the reaction conditions, the author found the best conditon: -15 oC, 0.1 mmol aldehydes, 2 equiv TMSCF3, 10 mol% combinatorial catalysts containing the disodium (R)-binaphtholate prepared in situ and a chiral quaternary ammonium salt, 10 mg 4 ? MS and 0.6 mL Et2O. The catalytic system catalyzed the trifluoromethylation of aromatic aldehydes and gave the products in 72-95% yield, with enantioselectivites 41-71% ee. A possible intermediate for the binaphtholate activation of the TMSCF3 and a catalytic cycle were proposed based on the experiments.