文摘
A palladium-catalyzed decarboxylative [4 + 3] cyclization of γ-methylidene-δ-valerolactones with 1,1-dicyanocyclopropanes has been developed to produce cycloheptane derivatives in a convergent manner. This method can be applied to the synthesis of azepanes by reacting with aziridines, and their asymmetric variants have also been described. In addition, selective ring-expansion reactions can be achieved for certain γ-methylidene-δ-valerolactones to give nondecarboxylated nine-membered lactones.