Palladium-catalyzed cross-addition of triisopropylsilylacetylene to unactivated alkynes

Selective cross-addition of triisopropyl silyl acetylene (TIPSA) to unactivated alkynes is catalyzed by dinuclear and mononuclear palladium complexes supported by a multidentate ligand, NN'-bis[2-(diphenylphosphino)phenyl]formamidine (dpfamH). While the addition reactions of TIPSA to dialkylacetylenes using palladium catalysts supported by monodentate and bidentate ligands gives dimers of TIPSA as major products, the reactions with the palladium complexes supported by dpfam affords cross-adducts selectively, in which the yields of TIPSA dimers are less than 5%. The addition of TIPSA to monoalkylacetylenes also gives cross-adducts as major products, although the selectivity and yield are moderate.