A Traceless Tether Strategy for Achieving Formal Intermolecular Hexadehydro-Diels–Alder Reactions

Smela, M. P.; Hoye, T. R. Org. Lett. 201820, 5502–5505. 

A synthetic strategy formally equivalent to an intermolecular hexadehydro-Diels–Alder (HDDA) reaction is described. Sulfur-based linkers were designed and constructed by joining terminal alkynes or diynes using alkyne thiolate chemistry. The resulting tetraynes and triynes successfully underwent HDDA cyclization and benzyne trapping. Linker removal by reductive desulfurization was uneventful. The strategy was also found suitable for the tetradehydro-Diels–Alder (TDDA) reaction.