Intermolecular Rh-catalyzed reactions of cyclic α-diazocarbonyl compounds with chemoselectivity over β-hydride elimination are described. These methods represent the first general intermolecular reactions of Rh-carbenoids that are selective over tertiary β-C–H bond migration. Successful transformations include cyclopropanation, cyclopropenation, and various X–H insertion reactions with a broad scope of substrates. We propose that the ...