Reactions of the nickelocene–dimethyl acetylenedicarboxylate adduct: a route to 7-substituted norbornadienes

Abstract

Contrary to an earlier claim, reactions of the complex (1) with m-chloroperbenzoic acid, N- bromosuccinimide, and N-chlorosuccinimide give the diester (15) and the syn-norbornadienes (2), (4), and (6), respectively; reactions of (1) with lead tetra-acetate and iodine also proceed with retention of C-7 stereochemistry but with bromine and chlorine inversion at C-7 is increasingly dominant.