19 ほおずきの苦味成分,Physalin AおよびPhysalin Bの構造

概要

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The bitter principles were isolated from Physalis Alkekengi var Francheti, and named physalin A and physalin B. Physalin A (C_<28>H_<30>O_<10>・CH_4O, mp. 260-2°, from methanol; C_<28>H_<30>O_<10>・C_3H_6O, mp. 265-6°, from acetone) (I) was converted into its tetrahydro-derivative (II), which was treated with Br_2-AcONa, affording an acetoxybromide (VII). An X-ray crystallographic analysis was carried out and the structure of the acetoxybromide (VII) was established, from which the structure of physalin A (I) was determined unequivocally. Physalin B (C_<28>H_<30>O_9・CH_4O, mp. 269-72°, from methanol; C_<28>H_<30>O_9・C_3H_6O, mp. 245-50°, from acetone) (VIII) gave an tetrahydro-derivative (X) on catalytic hydrogenation, which was also obtained by the hydrogenation of the acid-treatment product (XII) of physalin A (I). Thus physalin A (I) and physalin B (VIII) were correlated and the structure of the latter was established. Both physalin A and physalin B belong to a new type of C_<28>-steroids, the carbon skeleton of which has following two biogenetically interesting features: i) The C(13)-C(14) bond between rings C and D is broken resulting a nine-membered ring formation. ii) A bond is formed between C(16) and C(24) making a new six-membered carbocycle.
天然有機化合物討論会の論文
1969-09-01