A Rare Alder-ene Cycloisomerization of 1,6-Allenynes

Thermally induced cycloisomerization reactions of 1,6-allenynes gives alpha-methylene-gamma-lactams via intramolecular Alder-ene reactions. The mechanism is supported by computational and deuterium labelling studies. This thermal, non-radical method enables the discovery of a hitherto unknown route that proceeds via a divergent mechanism distinct from the previous [2+2] cycloisomerization manifold.

Automated summary

The thermally induced cycloisomerization reactions of 1,6-allenynes were studied, resulting in the formation of alpha-methylene-gamma-lactams through intramolecular Alder-ene reactions. Computational and deuterium labelling studies provided evidence for the proposed mechanism, and a divergent mechanism distinct from the previous [2+2] cycloisomerization pathway was discovered.