Site-Selective C_sp³–C_sp/C_sp³–C_sp² Cross-Coupling Reactions Using Frustrated Lewis Pairs

The donor–acceptor ability of frustrated Lewis pairs (FLPs) has led to widespread applications in organic synthesis. Single electron transfer from a donor base an acceptor acid can generate radical pair (FRP) depending on the substrate and energy required (thermal or photochemical) promote FLP into FRP system. Herein, we report Csp3–Csp cross-coupling reaction aryl esters with terminal alkynes using B(C6F5)3/Mes3P FLP. Significantly, when 1-ethynyl-4-vinylbenzene was employed, exclusive formation cross-coupled products observed. However, 1-ethynyl-2-vinylbenzene solvent-dependent site-selective Csp3–Csp2 resulted. nature these pathways their selectivity been investigated by extensive paramagnetic resonance (EPR) studies, kinetic density functional theory (DFT) calculations both elucidate mechanism coupling reactions explain site selectivity.