Facile synthesis of δ-ketoesters via formal two-carbon insertion into β-ketoesters

A formal two-carbon insertion into β-ketoesters with vinylmetal has been developed for the rapid synthesis of δ-ketoesters. This method features high efficiency, simple operation, and mild conditions without the usage of bases and catalysts. The reaction is postulated to proceed via a tandem process involving nucleophilic addition of vinylmetal to ketone, retro-aldol reaction to give an enolate anion and an enone, and finally Michael addition of these two intermediates.