16 テウリレンの全合成(ポスター発表の部)

抄録

Teurilene (1) is a marine triterpene isolated from the red alga Laurencia obtusa. The molecule of this compound is characterized by beautiful arrangement of eight asymmetric carbons in Cs symmetry, and it arouses special interest in its synthesis and conformational properties. We would like to report the first total synthesis of teurilene (1) and a short step synthesis by stereocontrolled double cyclization of a C_<30>-suqualene derivative 12. In the course of the studies on total synthesis of thyrsiferols (2) we found a "rule" of V^<5+> oxidation-cyclization of bishomoallyl alcohol system, i.e. a 5-substituted 4-en-1-ol 4 gave cis-2,5,-disubstituted tetrahydrofuran 6 through syn-epoxide 5, while 4-substituted 4-en-1-ol 7 gave trans-2,5,5-trisubstituted tetrahydrofuran 2 through anti-epoxide 8. This rule was extremely valuable to assemble stetreoselectively 2,4-substituted tetrahydrofuran moieties and usefulness was successfully demonstrated by application to the syntheses.