Synthesis of cyclopropanes through gold-catalyzed [2 + 1] cycloaddition of allenamides with sulfoxonium ylides.

Cyclopropyl groups are widely found in pharmaceutical products and their application as precursors or key reaction intermediates benefits the development of a wide range of reactions. Herein, we report a facile protocol for the synthesis of this compound through gold-catalyzed [2 + 1] cycloaddition of allenamides with sulfoxonium ylides. The reaction exhibited good functional group tolerance and high efficiency, affording the products in good to excellent yields with good diastereoisomerism. The steric hindrance between the sulfonamide group and the gold catalyst determined the major configuration of the formed -cyclopropane product. Moreover, the aldehyde could be converted to amide under Schmidt reaction conditions and alcohol under reduction conditions.