84(P-16) ホモケリドニンの立体選択的全合成(ポスター発表の部)

概要

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Biological active benzo[c]phenanthridine alkaloids can be classified into two categories of a partially hydrogenated-type and a fully aromatized-type alkaloid based on the oxidation stage of a basic skeleton. Many synthetic methods have been reported for the latter; however, only limited approaches have appeared on the former. We planned to synthesize the former homochelidonine (3) from a unique spirolactonyl tetralone, arnottin II (6), because of its successful correlation to chelerythrine (5), the latter alkaloid, in synthesis using a 2-benzofuranyl-1-tetralone (4) as a common key intermediate. Successive reactions of 6 by dihydroxylation, protection, oximation, and reduction gave a tetrahydronaphthylamine derivative (13). An isoquinoline skeleton (16) with all cis relations among the hetero atom substituents on the ring C was provided by reductive opening the spirolactone moiety of 13 followed by Mitsunobu reaction of the resultant N-trifluoroacetamide (15b). Removal of oxygen functions of 15b at the 10b and 12 positions was achieved under independent reduction conditions of catalytic hydrogenation and homolytic cleavage, respectively, after several modification to successfully afford (±)-homochelidonine (3). The overall yield of 3 from 6 was 11% in 15 steps.
天然有機化合物討論会の論文
2002-09-01