Ten compounds have been isolated from S. madagascariensis, generally in very small quantity and, where not previously known. their structures have been established by degradative and spectroscopic means, supported in two cases by synthesis. Three of these compounds, homopterocarpin (I1 ; R = Me), demethylpterocarpin (I ; R = H), and pterocarpin ( I ; R = Me) are known, whereas the remaining seven, 3-hydroxy-9-methoxypterocarpan (I1 ; R = H), 3-hydroxy-4-methoxy-8.9-methylenedioxypterocarpan (X), 3-hydroxy-4,9-dimethoxyp te roca rpa n ( XI11 ) , 3.4d i met h oxy-8,9met h y I e n ed i oxy p te roca rpa n (VI I), 3,4,9 -trim e t hoxy p te roca rpa n (XI), 3.9-dimethoxypterocarp-6a-en (XIV), and 3.9-dimethoxy-6-oxopterocarp-6a-en (XVI ; R = Me) have not been found previously in nature. The known 3,4,3',5'-tetrahydroxystilbene and homopterocarpin have been isolated from P. angolensis.Swartzia is a tropical genus of the Leguminosae (subfamily : Caesalpinioideae), consisting of 65 species, of which only one, S. madagascaviensis, is found in Rh0desia.l The heartwood of S. nzadagascariensis is purplish black, durable, and termite resistent. The seeds and pods have been shown to contain a glycoside of kaempferol and two sapogenins toxic to fish.3 Our investigation of S. rnadagascariensis has concerned only the heartwood with a view to identifying constituents responsible for the resistance to fungi and insects.The light petroleum extract consisted mainly of glycerides, as demonstrated by alkaline hydrolysis and paper-chromatographic identification of the glycerol. Subsequent ether-extraction gave a noncrystallisable red resin (up to 6% on dry weight), whose examination is the subject of this paper. Final ethanol extraction removed the purple pigment which, although chroinatographically homogeneous, could not be crystallised, and has not been further studied. Examination of the ether extract by t.1.c. indicated the presence of five components, which were separated by a combination of preparative t .l.c. and column chromatography. Despite being cliromatographically hoinogeneous four of these components did not behave as pure conipounds. Examination by g.1.c. revealed that each was a mixture of two or more compounds and a total of 10 compounds was present in the resin. Those fractions ( R p 0.55 and 0.61) which were insoluble in aqueous sodium hydroxide were separated into their constituents by fractional crystallisation. Those fractions (X, 0.14 and 0.22) which were soluble and contained phenolic hydroxy-groups, but gave no colour with ferric chloride, could not be separ-

Jan., 1950 4,5-BENZTROPOLONE AND RELATED COMPOUNDS 379 2. Picrasmin and isoquassin are identical. 4. Neoquassin (GHsoOa) is a hydroxy com-3. Quassin is a molecular complex containing pound and isoquassin (CztHtsOa) is the correisoquassin and neoquassin in approximately sponding ketone. equal amounts.

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Seven compounds, five of them new, have been isolated from the heartwood of Diospyros guiloensis. The new compounds have been shown by chemical and spectroscopic methods, and by synthesis, to be 4, 5,6,8-tetramethoxy-, 5-hydroxy-4,6,8-trimethoxy-, 4,5,8-trimethoxy-, 4,5-dimethoxy-, and 5-hydroxy-4-methoxy-2-naphthaldehyde. The other two, 4.5.6-trimethoxy-and 6-hydroxy-4,5-dimethoxy-2-naphthaldehyde, have been isolated previously from a Diospyros species.Related methoxynaphthoic acids and methoxynaphthaldehydes have been synthesised by Stobbe condensation and cyclisation. The structures of the compounds derived by cyclisation of the mono-and bis-condensation products of 3.4-dimethoxybenzaldehyde with ethyl succinate have been determined on the basis of spectral considerations and explained on stereochemical grounds.The n.m.r. spectra of these substituted naphthoic acids and naphthaldehydes confirm the importance of the peri-effect and the large deshielding by an 8-methoxy-group on a proton in the 1 -position.THE EBENACEAE is one of the smaller families of flowering plants, having only three genera; of these, Diospyros is by far the largest, with about 500 species.l The family is widespread in the tropics and 18 species occur in Rhodesia, of which 12 belong to the genus Dio~pyros.~ Chemical examination of the Ebenaceae has been mainly confined to the Diosfiyros genus, naphthoquinones and other naphthalene derivatives have been i ~l a t e d . ~ Our interest in this genus was aroused because of reports of the use of the fruits of some species as fish poisons; several species are termite resistent, and compounds toxic 1

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