50(PA1-8) 抗腫瘍性quassinoidsの合成研究(ポスター発表の部)

概要

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Synthetic studies on antileukemic quassinoids, bruceantin (1) and related compounds (2), (3), and (4), have been carried out in order to obtain some informations on the structure-activity relationship. The tetracyclic diol (17), the key intermediate in this strategy, was synthesized stereoselectively from readily available Wieland-Miescher ketone (5) via 27 steps. The key transformations include the intramolecular aldol cyclization of highly hindered 1,5-diketone (7) and the regio- and stereoselective epoxidation of the allylic alcohol (16) followed by the acid-catalyzed epoxide ring opening to form the tetrahydrofuran ring. The pentacyclic diol (24), which satisfies all requirements for bruceantin skeleton, was synthesized in 10 steps from 17. Construction of the trans diaxial diol system in the C-ring of (1), (2), (3), and (4) was accomplished by utilizing the method of Fuchs: (i) cis hydroxylation of 28 to 29; (ii) regioselective oxidation of 29 to ketol (30); (iii) reduction of 30 to trans diol (31) and 29 (3: 1,respectively). The pentacyclic lactone (41), having complete carbon skeleton and desirable functional groups at suitable positions, was synthesized from 17 via 19, 28, and 39. Further syntheses toward bruceantin (1) and related quassinoids (2), (3), and (4) are under way.
天然有機化合物討論会の論文
1987-07-25