Abstract
Several regiochemical and stereochemical problems are discussed, the solution of which resulted in the total synthesis of cytochalasin B and A. I. Diels-Alder reaction of triene and conversion of Δ^<6,7> to Δ^<6,12> 7-hydroxy system. II. Problems in the introductions of benzyl group and angular hydroxyl group. III. Regiochemical considerations of Diels-Alder adducts. IV. Preparation of the optically active dienophile 86. V. Preparation of the triene 111. VI. Diels-Alder reaction between the triene 111 and the dienophile 86 gave the adduct 113 possessing the desired stereochemistry as the major product. Reductive cleavage of the bromoepoxide 116 afforded Δ^<6,12>-7-hydroxy compound 117 which satisfied all the chiral centers of cytochalasin B. Extension of two carbons on the side chain and subsequent saponification completed the formal total synthesis.
