Choline Chloride-BasedDeep Eutectic Systems in Sequential Friedländer Reaction andPalladium-Catalyzed sp3 CH Functionalization of MethylKetones

摘要

A volatile organic solvent-free and choline chloride (ChCl)-based deep eutectic system (DES)-mediated sp³-CH functionalization of acetophenones >1 with benzyl alcohols >2 to the corresponding α, β-saturated ketones >3 is accounted for. The domino dehydrogenation–aldol condensation (hydrogenation borrowing concept) has been successfully attempted with palladium-tetrakis(triphenylphosphine) [Pd(PPh3)4] catalyst–xantphos ligand combination. Furthermore, a sequential Friedländer reaction of 2-aminobenzophenone >4 and palladium-catalyzed α-alkylation of the quinolinyl methyl ketone with benzyl alcohols >2 in ChCl-based DES have been successfully investigated. The C–C bond formation through sp³-CH functionalization involves a wide scope of the substrates, high atom efficiency, chemoselectivity, and environmentally friendly strategy.