10.1016/S0040-4020(01)86222-0
The study investigates cyclopentaannulation reactions between nitrocycloalkenes and diacetyl morpholino enamine. The key chemicals involved are 3-(4-morpholinyl)-3-buten-2-one, acting as an enamine substrate, and cyclic nitroolefins such as 1-nitrocyclopentene and 1-nitro-cyclohexene. The researchers found that reacting the enamine with 1-nitro-cyclohexene produced a [4 + 2] heterocyclization intermediate, while an unusual double addition product was obtained from the hexahydro-pentalene derivative in aqueous acidic medium. The study explores the formation, stability, and transformations of various products, including enamine derivatives and their corresponding ketones, providing insights into the stereochemistry and reaction mechanisms involved in these cyclopentaannulation processes.