A Practical Synthesis of β-KetoThioesters by Direct Crossed-Claisen Coupling of Thioesters and N-Acylbenzotriazoles

Thioesters undergo chemoselective soft enolization and acylation with N-acylbenzotriazoles on treatment with MgBr 2 ·OEt 2 and i-Pr 2 NEt to give β-veto thioesters. Prior enolate formation is not required and the reaction is conducted using untreated dichloromethane open to the air.