Reactions with aziridines - 39. Ring opening of activated 2,2-dimethylaziridines by grignard reagents. A mechanistic study

Article abstract of DOI:10.1016/S0040-4020(01)89990-7

Reaction of activated 2,2-dimethylaziridines 1 with Grignard reagents RMgHal in boiling THF can yield the products 2 of normal aziridine ring opening, the rearranged opening products 3, and the methallylamides 4 (isomers of 1 ). The product distribution depends on R, Hal, and experimental conditions, and very strongly on the nature of the activating group A. It is shown that 1 is opened (reversibly for A = sulfonyl) forming 10 through a Lewis acid assisted attack of Hal^θ on the tert carbon of 1 (abnormal opening by Hal^θ ). Evidence is presented to show that 4 as well as 3 come from this intermediate.