The trunk wood of Pterodon pubescens Benth. (Leguminosae-Lotoideae) contains 3',4',6,7-tetramethoxyisoflavone (Ia), 2',6,7-trimethoxy-4',5'-methylenedioxyisoflavone (Ib) and 2',3',4',6,7-pentamethoxyisoflavone (Ic). Pterodon pubescens Benth. (Leguminosae-Lotoideae) is native to the savannahs of Central and Southern Brazil. The fruits contain geranylgeraniol, all-trans(-)-14,15-epoxygeranylgeraniol,3 besides two additional diterpenes4 and alkaloids.5 The wood is suitable for joists and railroad ties.6 Fractional crystallization of its benzene extract yielded a new compound, in addition to 3',4',6,7-tetramethoxyisoflavone (Ia), which was synthesized7 prior to its isolation from the heartwood of Cordyla africana, and 2',6,7-trimethoxy-4',5'-methylenedioxyisoflavone (Ib, milldurone), a constituent of Cordyla africana* and of Millettia dura.9 The IR and UV spectra showed that the new compound, C₂₀H₂₀O₇, was an isoflavone. This indication was reinforced by the NMR spectrum which contained the signal at 2.05 τ due to the isoflavonoid 2-H, and revealed the presence of 5 methoxyls and of 4 aromatic protons. The chemical shifts of two singlets (2.35, 3.10 τ) allocated two of these protons to the para-positions of ring A, while the chemical shifts and coupling constant of two doublets (3.25, 2.93 τ, J 9.1 Hz) allocated the remaining two protons to the 5',6'-positions of ring B. Hydrogenation to the isoflavanone caused the following diamagnetic shifts of the aromatic