Acid‐Free Nickel Catalyst for Stereo‐ and Regioselective Hydrophosphorylation of Alkynes: Synthetic Procedure and Combined Experimental and Theoretical Mechanistic Study

Abstract

Abstract The nickel catalyst prepared in situ from nickel bis(acetylacetonate) [Ni(acac) 2 ] precursor and bis(diphenylphosphino)ethane (DPPE) ligand has shown excellent performance in the hydrophosphorylation of alkynes. Markovnikov‐type regioselective addition to terminal alkynes and stereoselective addition to internal alkynes were carried out with high selectivity without an acidic co‐catalyst (in contrast to the palladium/acid catalytic system). Various H‐phosphonates and alkynes reacted smoothly in the developed catalytic system with up to 99% yield. The mechanisms of catalyst activation and CP bond formation were revealed by experimental (NMR, ESI‐MS, X‐ray) and theoretical (density functional calculations) studies. Two different pathways of the alkyne insertion in the coordination sphere of the metal are reported for the first time.