Abstract
Ircinal A (1) was isolated from Okinawan marine sponges by Kobayashi. Ircinal A (1) and Manzamine A (2) have been the subject of recent synthetic investigations owing its unique molecular structure and remarkable biological properties including antitumor and antibacterial activities. We have already accomplished a synthesis of key tetracyclic intermediate (ABCD ring) for 1 and 2 in a racemic form. For the synthesis of optically active 1 and 2, several optically active dienophiles (11, 16, 17, 26) were prepared and subjected to Diels-Alder reaction with Danishefsky diene. The D-A adduct, obtained by the reaction of dienophile (16), was successfully converted to the tetracyclic intermediate (3), in an optically active form.
