Activation of Alkynes by a Redox-Active Carboranyl Diphosphine and Formation of Boron-Containing Phosphacycles.

In this work, we report the reactivity of the carboranyl diphosphine, 1-P t Bu 2 -2-P i Pr 2 -C 2 B 10 H 10 , with terminal alkynes, resulting in the formation of boron-containing phosphacycles. The reported system combines the nucleophilic activation of electron-deficient terminal alkynes via electron-rich phosphine groups with the redox behavior of carborane clusters to promote a sequence of metal-free intramolecular B-H bond activation and cyclization, creating an alkenylphosphonium cycle fused with a reduced open nido -carborane cluster.