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.