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In order to obtain novel lead compounds with potent
antiallergic and anti-inflammatory activities,
6,7,4'-substituted isoflavanquinones were synthesized and
evaluated for bioactivities. 6,7,4'-substituted
2'-benzyloxyisoflavone (Ⅴ1∼Ⅴ3), the key intermediate,was
synthesized through the oxidative rearrangement of
4,4',5'-substituted 2-benzyloxy-2'-hydroxychalcone (Ⅱ1∼Ⅱ3)
with thallium(Ⅲ) nitrate. The product Ⅴ1∼Ⅴ3 was then reduced
by catalytic hydrogenation on Pd/C to the corresponding
6,7,4'-substituted 2'-hydroxy-isoflavan (Ⅵ1∼Ⅵ3) with loss of
the benzyl group. 6,7,4'-Substituted 2'-hydroxyisoflavan (Ⅵ1∼
Ⅵ3) was furtheroxidized with Fremy's salt to give the target
compound 6,7,4'-substituted isoflavanquinone (Ⅶ1∼Ⅶ3). The
target compounds Ⅶ1∼Ⅶ3 and its related compounds were
evaluated for their antiallergic and anti-inflammatory
activities. Among compounds tested, 3-quinonyl derivatives,
namely 4'-methoxy-isoflavanquinone (Ⅶ1),
7-methoxyisoflavanquinone (Ⅶ2), 6-fluoro-isoflavanquinone
(Ⅶ3), 4'-methoxyisoflavonequinone (Ⅸ1), 7-methoxy-
isoflavonequinone (Ⅸ2) and 6-fluoroisoflavonequinone (Ⅸ3) were
the most promising agents, which provide a novel structural
prototype for antiallergic and anti-inflammatory agents.
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