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THE investigations of Ruzicka, and of Winterstein and their co-workers, have shown that the majority of the triterpene acids (hederagenin, gypsogenin, oleanolic acid, sia- and suma-resinolic acids) are in all probability θ-hydroxy-γ: δunsaturated mono-basic acids, as indicated in the accompanying formula1. Onthe other hand, β-boswellinic acid, C29H46(OH)COOH, one of the principal triterpene constituents of frankincense, evidently possesses a somewhat different constitution, for on mild oxidation with chromic anhydride this acid is converted into a monoketone C29H46O, m.p. 196° (found: C, 84·53; H, 11·11. C29H46O requires C, 84·80 ; H, 11·30 per cent), which has been characterized by the preparation of an oxime. Oxidation under similar conditions of β-boswellinic methyl ester, however, furnishes the corresponding keto-ester, m.p. 160° (found: C, 79·12 ; H, 10·20. C31H48O3 requires C, 79·41 ; H, 10·33 per cent), which forms an oxime, m.p. 200°.

Aus der Fleischschale der Nusse vonSapindus laurifolius wurden ausser Hederagenin 2 Triterpene isoliert. Das eine wurde als Oleanolsaure identifiziert, und das andere (Sapindic-Saure) erwies sich als Δ12 3Σ,23α-oxido-oleanen-28-saure.