Our examination of the heartwood of Gmelina arborea Linn.(Verbanaceae), resulted In the Isolation of a new llgnan now named arboreal (I), besides gmellnol (II) isolated earlier by Birch et al.l from Gmellna leichhardtli. bo eol (I), @ C21iQGO8, n+ 400, m.p. 3x0 135O, MD + 84.5' (c, 1.0, cHc13), Cl3 3537 (OH), 2829 (OCH3), 2769, 936 (0-Cl$-O) and 1602 cm-', on oxid ion with Cr03/HCAc, afforded piperonyllo acid in an yield of 612 suggesting two plperonyl units in the molecule. Further, arboreol (I) contained a tertiary hydroxyl reslstant to acetylatlon. The NM8 spectrum of arboreal (I) (Table-I) Is charaoteriatically similar to gmellnol (II) and confirms a furofuran nucleus In this lignan. The aromatic region together with the methylenedloxy signals atS3.926, 3.976, also confirms the presence of two non-equivalent plperonyl.nuclell in the molecule. The sharp singlet atr6.87 Integrates for one methoxyl suggesting an alkyl methoxyl. This upfleld signal for a methoxyl can be satisfactorily explained If it Is located at C-2 to which the plperonyl ring Is also attached. The only one benzyllc hydrogen appears as a doublet atT5.40, J=7ops, which is taken to confirm Its p -axial position at c-6 trans to the bridgehead hydrogen at C-5. The resonances of methylene hydrogen6 at c-8 and C-4 are signlficantly Influenced by the two aryl substltuents at C-2 and ~-6~. The methylene hydrogen6 at C-4 appear as a pair of quartets atT6.02 andT5.72, similar to those noticed In iso-and neogmellnols2. It Is, therefore, inferred that the c-6 aryl group must be equatorial as in lso-and neogmellnols. Slmllar oonsl-
derations on the interaction between the C-2 plperonyl group and C-8 methylene hydrogens (r6.60 and 6.12) will suggest an axial position for this aryl group. The hydroxyl is noticed atT 6.35d,J=1.5cps and when exohanged with 2179