Oxetan-3-ones from allenes via spirodiepoxides.

Two concise methods for generating oxetan-3-ones from allenes are reported. The first method employs allene epoxidation, opening of the spirodiepoxide by a halide nucleophile, and then intramolecular displacement of a halide by an alkoxide. The second method involves allene epoxidation and then thermal rearrangement of the corresponding spirodiepoxide to oxetan-3-one. The two methods are complementary and stereochemically divergent. Computational analysis of the thermal rearrangement is also described.