Synthesis of vinca alkaloids and related compounds XXXVIII: Formation of dimers under Polonovski reaction conditions

Abstract

Abstract The dimeric products ( la‐c ) have been prepared by treatment of N ‐oxides derived from some indole alkaloids. Their structures have been elucidated by detailed NMR investigations and the structure of 1c determined by X‐ray analysis. The importance of the E 2 ‐type trans ‐axial elimination of the N ‐acyloxy intermediate in the dimer formation has also been established. The iminium salts 4a‐b and the derived pseudocyanide 6 have been prepared.