In an attempt to prepare adamanto[1,2-d]oxazolidin-2-one (2), 2-adamantyl azidoformate was subjected to photolysis in cyclohexane. The main product 8 (yield 41%) is formed by intermolecular insertion of the nitrene in the solvent. The only other pure compound isolated (yield 15%) is a product of intermolecular insertion. The i.r. spectrum of the latter supports the presence of a five-membered cyclic carbamate. The fact that intermolecular insertion is the main reaction is unexpected in view of the results reported by others.