Tandem Asymmetric Aza-Darzens/Ring-Opening Reactions

Significance

This is a paper from Leighton’s series of works based on chiral silyl reagents. Enantiomerically pure aziridines are synthetically important intermediates, which can be converted into a large number of products via ring opening by nucleophiles. In this paper, the authors successfully attempted a one-pot sequence of aza-Darzens ­reaction and opening of the formed aziridine ring. The stoichiometric use of the chiral silane resulted in a highly regio- and enantioselective process. Instead of a chloride anion, variously substituted indoles can be used as nucleophiles in the presence of zinc chloride. A number of functionalized heterocycles, for example 1-3, can be easily prepared from the reaction products.