Four isoflavones from seed pods of Millettia dura

Seed pods of Millettia dura yielded four novel isoflavones, which have been characterized as 3-(3,4-dimethoxyphenyl)-6-methoxy-8,8-dimethyl- 4H,8H-benzo[1,2-b: 3,4-b']dipyran-4-one (trivial name, durallone), 6-demethyldurallone, 3-(3,4-dimethoxyphenyl)-8-(3-methylbut-2-enyl)-6-methoxy-7-hydroxybenzopyran-4-one (trivial name, predurallone) and 3-(4-{3-methylbut-2-enyloxy})-8,8-dimethyl-4H,8H-benzo[1,2-b: 3,4-b']dipyran-4-one (trivial name, isoerythrinin-A 4'-(3-methylbut-2-enyl) ether. Structures of these compounds were determined on the basis of their spectroscopic data.