2-dihydropyridines such as 26 or 27. Diene 21 was also shown to give diastereoisomeric cycloadducts 30 or 32 with enamines or oxazolidine derivatives. The cycloadducts 30 were finally shown to react with n-butylamine in acidicmedium to give rearranged cyclopentenes 36 and 37. Although the synthesis of derivatives such as 9 or 10, corresponding to the AB ring system of manzamine A, by this approach have yet