BF3-Induced Rearrangement of Aziridinocyclopropanes Derived from 2-Phenylsulfonyl-1,3-Dienes. A New Approach to the Tropane Alkaloid Skeleton

Article abstract of DOI:10.1016/0040-4039(96)00549-7

Five N-substituted derivatives of 1,2-methylene-3,4-aziridino 2-phenylsulfonyl cycloalkanes (3a-e) were prepared from their corresponding epoxy cyclopropanes via ring opening of the epoxide by sodium azide and subsequent triphenlphosphine induced cyclization.BF3-induced reaction of compounds 3a-e resulted in a rearrangement via a cyclopropyl carbinyl cation intermediate.In the case of tosylaziridine 3c bicyclic product 5, (tropane skeleton), was formed as the major product.With carbamate derivative 3a exclusive rearrangement to fluorocycloheptene 7 took place.