Preparation of γ,δ-unsaturated-β-ketoesters: Lewis acid-catalysed C[sbnd]H insertion of ethyl diazoacetate into α,β-unsaturated aldehydes

The synthesis of γ,δ-unsaturated-β-keto esters was achieved by the Lewis acid-catalysed direct C[sbnd]H insertion of an α-diazoester into various α,β-substituted-unsaturated aldehydes. C[sbnd]H insertion of ethyl diazoacetate into alkyl- and aryl-substituted α,β-unsaturated aldehydes was performed under mild conditions to afford the corresponding γ,δ-unsaturated-β-keto esters in moderate to high yields as a mixture of keto/enol tautomers.