An unusual and efficient reaction of 2-methylene-3-phenyloxetane in the presence of lithium and 4,4′-di-tert-butylbiphenyl in THF

When 2-methylene-3-phenyloxetane (4) was treated with excess lithium and DTBB (cat.), lactone 6 was isolated as an unexpected product in high yield. It is postulated that 6 arises from a coupling of a radical enolate derived from 4 and the enolate of acetaldehyde, a product of THF decomposition under the reaction conditions.