Modular Access to Substituted Azocanes via a Rhodium-Catalyzed Cycloaddition–Fragmentation Strategy

A short entry to substituted azocanes by a Rh-catalyzed cycloaddition–fragmentation process is described. Specifically, exposure of diverse N-cyclopropylacrylamides to phosphine-ligated cationic Rh­(I) catalyst systems under a CO atmosphere enables the directed generation of rhodacyclopentanone intermediates. Subsequent insertion of the alkene component is followed by fragmentation to give the heterocyclic target. Stereochemical studies show, for the first time, that alkene insertion into rhodacyclopentanones can be reversible.