Additive-Free Conversion of Internal Alkynes by Phosphanylalumanes: Production of Phosphorus/Aluminum Frustrated Lewis Pairs.

Internal and terminal alkynes react with phosphanylalumanes, i. e., P-Al single-bond species, through heating but without any additional additives. The reactions with internal alkynes afforded the corresponding adducts with cis-1,2-form in moderate yields (54-80 %). In addition, alkyne adducts thus obtained function as P/Al-based C -vicinal FLPs, and the FLP addition reactions with benzaldehyde and CO were demonstrated. Furthermore, in the reaction of 2,4,6-trimethylphenyl-substituted alkyne adducts with dimethyl acetylenedicarboxylate, an unexpected C -C bond cleavage characteristic of this system was demonstrated.