Cu-Promoted Divergent Phosphination of Alkynylsulfonium Salts with Diarylphosphines

An efficient copper-promoted divergent phosphination of alkynylsulfonium salts 1 with secondary diarylphosphines 2 that tolerates a wide range of functional groups under mild conditions is reported. The use of excess alkynyl dibenzothiophenium salts (1/2 > 1, mole ratio) enables the phosphination to deliver alkynyl monophosphine products via a C(sp)–P cross-coupling in good to high yields, while the use of excess secondary diarylphosphines (1/2 < 0.5, mole ratio) leads to a type of cis-ethenyl bisphosphine products via sequential stereoselective double phosphination.