Organic Letters 2009-12-17

Palladium-catalyzed decarboxylative [4 + 3] cyclization of gamma-methylidene-delta-valerolactones with 1,1-dicyanocyclopropanes.

Ryo Shintani, Masataka Murakami, Takaoki Tsuji, Hideyuki Tanno, Tamio Hayashi

Index: Org. Lett. 11(24) , 5642-5, (2009)

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Abstract

A palladium-catalyzed decarboxylative [4 + 3] cyclization of gamma-methylidene-delta-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 gamma-methylidene-delta-valerolactones to give nondecarboxylated nine-membered lactones.