Rh(II)-Catalyzed Spirocyclization of α-Diazo Homophthalimides with Cyclic Ethers.

Rh(II)-catalyzed decomposition of α-diazo homophthalimides in the presence of cyclic ethers gave spirocyclic products of Stevens-type [1,2]-alkyl shift within the postulated oxonium ylide intermediate. Such a reaction pathway is in line with thermodynamic predictions obtained from quantum chemical calculations performed at the B3LYP/6-31G* and B3LYP/6-311++G** levels of theory. These findings represent the first systematically investigated case of spirocyclization of cyclic α-diazocarbonyl compounds with cyclic ethers.