Bismuth Triflate-Chiral Bipyridine Complex Catalyzed Asymmetric Ring Opening Reactions of meso-Epoxide in Water

Abstract

Catalytic asymmetric ring-opening reactions of meso-epoxides with aromatic amines have been explored.The reactions proceeded in the presence of a catalytic amount of bismuth triflate (Bi(OTf) 3 ), chiral bipyridine ligand (1) and sodium dodecylbenzene sulfonate (SDBS) in pure water to give the corresponding β-amino alcohols in good yields with high enantioselectivities.The exploration of enantioselective reactions using chiral Lewis acids in water is one of the most fascinating topics in current organic chemistry.Not only do such reactions provide novel routes to compounds of great synthetic import, but are also very attractive from an environmental standpoint due to their environmentally benign nature. 1 For such reactions to proceed efficiently it is critical that the Lewis acids employed be compatible with water.Conventional Lewis acids such as titanium chloride, aluminium chloride, etc. which are known to be highly moisture sensitive, undergoing rapid decomposition on contact with water are therefore, in general, unsuited to this purpose.Bismuth triflate (Bi(OTf) 3 ), however, is reported to exist in water as an equilibrium mixture of Bi(OTf) 3 with bismuth hydroxide and triflic acid. 2 Up to today, only a few examples of enantioselective reactions using a chiral bismuth catalyst have been reported. 3Quite recently, we have achieved asymmetric hydroxymethylation