Insight into the structure of the precatalyst and active species for samarium iodo binaphtholate catalysed aminolysis of epoxides

Samarium iodo binaphtholate is an efficient Lewis acid catalyst for the enantioselective carbon–nitrogen bond formation such as aza-Michael reactions and the aminolysis of epoxides allowing highly enantioenriched aminoalcohols and aminoacids building blocks to be prepared. Various studies including the relationship between enantiomeric excess and temperature and observation of non linear effects for these reactions indicate the importance of the amine for the formation of the catalytic species. Results support the proposal of dimeric or more aggregated structures for samarium iodo binaphtholate and of a bimetallic active species for the aminolysis of epoxides.

Graphical abstractDimeric structures for complex 1 and for the active species in above reactions have been proposed on the basis of isoinversion of ee with temperature and non linear effects.Figure optionsDownload full-size imageDownload as PowerPoint slide

(3R, 4R)-tert-Butyl 3-hydroxy-4-(2-methoxyphenylamino)pyrrolidine-1-carboxylateC16H24N2O4Ee = 62%[α]D25=+15.7 (c 1.0, CHCl3)Source of chirality: enantioselective aminolysis of epoxidesAbsolute configuration: (3R,4R)