Rhodium-catalyzed tandem addition-cyclization of alkynylimines

A rhodium-catalyzed tandem addition-cyclization of alkynylimines is described. In this process employing a single rhodium catalyst, alkyne-tethered N-sulfinyl and sulfonylimines react with aryl/alkenylboronic acids and aryl/alkyl zinc reagents to give 2-alkylidene-substituted cyclobutyl and cyclopentyl amine products. The reaction occurs through a tandem sequence involving 1,2-carbometalation of the alkyne and 4- and 5-exo-cyclization of the resulting alkenyl rhodium with the imine. This method allows for the catalytic alkyne addition/cyclization process to include imine substrates, providing expeditious access to complex cyclobutyl and cyclopentyl amines with potential stereocontrol.