Cationic Rhodium(I) Complex-Catalyzed [3 + 2] and [2 + 1] Cycloadditions of Propargyl Esters with Electron-Deficient Alkynes and Alkenes

摘要

Catalytic cycloadditions via metal carbene intermediates have been extensively studied, and a number of efficient methods are available. However, the majority of reports involve cycloadditions with electron-rich unsaturated compounds because of the electrophilic nature of metal carbene intermediates. Recently, several notable examples employing electron-deficient unsaturated compounds were reported. For cyclopropanations of electron-deficient alkenes with diazo compounds, Ru(II)/salen or Co(II)/porphyrin complex-catalyzed reactions were reported.