Synthesis of α-Diketones by Direct, Low-temperature, in Situ Nucleophilic Acylation of Esters by Acyllithium Reagents

Article abstract of DOI:10.1021/jo00020a014

Addition of n-, sec-, or tert-butyllithium to a CO-saturated solution of an ester, R'CO2R'' in a solvent system of 4:4:1 (by volume) THF/Et2O/pentane at -110 deg C (or at -135 deg C in 3:1 (by volume) Me2O/THF), followed by hydrolysis with saturated aqueous NH4Cl, results in the formation of α-diketones, BuC(O)C(O)R', yellow liquids, in good yield.Similar reactions with diethyl succinate gave in one instance both t-BuC(O)C(O)CH2CH2CO2Et and t-BuC(O)C(O)CH2CH2C(O)C(O)Bu-t.The monoacylation product of dimethyl oxalate, t-BuC(O)C(O)CO2Me, readily formed a crystalline hydrate, t-BuC(O)C(OH)2CO2Me.