Synfacts 2010(10): 1119-1119  
DOI: 10.1055/s-0030-1258617
Synthesis of Heterocycles
© Georg Thieme Verlag Stuttgart ˙ New York

Mg-Catalyzed Dynamic Asymmetric Synthesis of Chiral Pyrrolidines

Contributor(s): Victor Snieckus, Timothy Hurst
A. T. Parsons, A. G. Smith, A. J. Neel, J. S. Johnson*
University of North Carolina at Chapel Hill, USA
Further Information

Publication History

Publication Date:
22 September 2010 (online)

Significance

The Mg-catalyzed enantioselective synthesis of 2,5-cis-disubstituted pyrrolidines 3 is reported via a dynamic kinetic asymmetric [3+2] annulation of racemic cyclopropanes 1 with (E)-imines 2. Extensive optimization of the imine N-protecting group showed that the 2-methoxybenzyl substituent gave the best yield and stereoselectivity. Electron-rich and -neutral aryl imines provided high yields and enantioselectivities of pyrrolidines 3. Electron-poor aryl, alkenyl, and ­aliphatic imines were not competent coupling partners. Electron-rich donor groups (R¹) are also required. Based on mechanistic studies and stereochemical observations, reaction of the imine through the E-geometry via an unusual diaxial transition state is suggested.