Cationic Ruthenium Complex of the Formula [RuCl(2,6-Diacetylpyridine)(PPh3)2]BArF and Its Catalytic Activity in the Formation of Enol Esters

A new ruthenium 2,6-diacetylpyridine complex was synthesized and applied in the atom-economic synthesis of enol esters through Markovnikov-directed addition of carboxylic acids to terminal alkynes. The ruthenium complex [RuCl(dap)(PPh 3 ) 2 ] + BArF −  was synthesized from [RuCl 2 (PPh 3 ) 2 ] and the corresponding ligand 2,6-diacetylpyridine (dap). The complex was characterized structurally. The new ruthenium complex was utilized under ambient conditions as a catalyst in the Markovnikov addition of carboxylic acids to terminal alkynes to afford the corresponding enol esters in 93% to 52% isolated yields (85 °C, 16 h reaction time, 1 mol% catalyst loading).