Pyrrolidinone-fused cyclohexenones by regioselective dearomatising anionic cyclisation of 2-, 3- or 4-methoxybenzamides

On treatment with t-BuLi in the presence of HMPA, 2-, 3- or 4-methoxybenzamides (o-, m- or p-anisamides) bearing N-benzyl substituents cyclise with dearomatisation to give methyl dienyl ethers which hydrolyse to give single stereo- and regioisomers of pyrrolidine-fused cyclohexenones. The bicyclic enones are versatile synthetic intermediates which undergo transformations such as stereoselective reduction and conjugate addition, regioselective Baeyer-Villiger oxidation, bromination and hydrogenation.