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Manzamines and ircinals are a group of naturally occurring β-carboline alkaloids isolated from the Okinawan sea since 1986, which are distinguished by the unprecedented polyazacyclic structure as well as potent antitumor and antibacterial activity. Of special interests are the recent isolation of the closely related alkaloids (ircinals and other polyamines) and ingenious proposal for their biosynthesis. For the challenging construction of the complex hydroisoquinoline framework of manzamine A and ircinal A, we have investigated the feasibility of the Diels-Alder reaction of the suitably protected 3-alkyldihydropyridinones. Through an efficient intermolecular D-A reaction of the N-arylsulfonyldihydropyridinone and Danishefsky's diene, we have successfully constructed the central tetracyclic core (1, ABCD ring system) of manzamine A. As a pursuit for the most refined route to obtain the chiral product, chiral azocine-containing dihydropyridinone (2) was emerged to be an ultimate dienophile to be employed. For the preparation of this new dienophile as an optically active form, novel synthetic method to costruct azocin ring was devised, as well as an efficient route to the chiral dienophiles starting from L-serine derivative.