Reactivity of Morita-Baylis-Hillman Adducts in C-H Functionalization of (Hetero)aryl Nitrones: Access to Bridged Cycles and Carbazoles

The rhodium(III)-catalyzed cross-coupling of (hetero)aryl nitrones with Morita-Baylis-Hillman (MBH) adducts is described. An allylated intermediate derived from aryl nitrones and MBH adducts allows the formation of bridged cyclic compounds via an exotype [3 + 2] cycloaddition. In sharp contrast, electron-rich indolinyl or aniline substrates were found to couple with MBH adducts to generate naphthalene or carbazole derivatives, respectively.