and references therein.(11) Subtle differences of energy content of the two dienes 4 are noted also from a study of equilibration of their nuclear double bonds [E. Wenkert and Z. Kumazawa, ibid., 140 (1968)]. While 4a remained unfazed, acid-induced isomerization of 4b led to an equilibrium mixture of 2a, 4b, and sandaracopimaradiene.

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Chemical investigation of the glycosidic constituents of Oospora virescens (Link) Wallr. resulted in the isolation of several glycosides. We have shown recently [l] that two of them, named virescenoside A (I) and B (11) are p-D-altropyranosides of virescenol A and B; these diterpenic aglycones have been found to have the structure of isopimaradien-2cu,3p-l9-triol (IV) and isopimaradien-3,9,19&01 (V), respectively [2].I n this paper we describe the isolation and structure of virescenoside C, a new metabolite of

Aufgrund chemischer Reaktionen (Hydrolyse, Acety1ierung, Reduktion) und Massen‐ und NMR‐spektroskopischer Untersuchungen werden für die Titelmetaboliten Virescenosid D bzw. Hdie Strukturen (IIb) bzw. (IId) ermittelt.