A new look at the McMurry reaction

Abstract

The article emphasizes the contradictory features of the McMurry reaction. The historical view shows how the chemists were firmly convinced of the occurrence of pinacolate intermediates and rejected, in spite of some evidence, the alternative pathway via carbenoid species. The McMurry reaction continues to find new important applications but suffers from problems of reproducibility. New practical reagents and simplified methods have been developed but rather complicated systems have been designed for obtaining higher selectivities. Recent investigations confirmed that pinacolates would be the precursors to alkenes but also revealed the possible involvement of carbenoid species, putting forward the dual nature of the mechanism of the McMurry reaction.