Stoffwechselprodukte von Mikroorganismen. 186. Mitteilung . Über die Aspochalasine A, B, C und D

Metabolites of Microorganisms. The Aspochalasins A, B, C, and D The structures of the antibiotic aspochalasin B (asposterol) and its inactive co‐metabolites aspochalasin A, C, and D from Aspergillus microcysticus (Tü 502) were elucidated by extended spectroscopic studies and chemical degradation. The structures are: aspochalasin A = 10‐isopropyl‐14‐methyl[11]cytochalasa‐6, 13‐dien‐1, 17, 18, 21‐tetrone ( 32 ), aspochalasin B = 17‐hydroxy‐10‐isopropyl‐14‐methyl‐[11]cytochalasa‐6, 13, 19‐trien‐1, 18, 21‐trione ( 11 ), and aspochalasin C = 17, 18‐dihydroxy‐10‐isopropyl‐14‐methyl[11]cytochalasa‐6, 13, 19‐trien‐1, 21‐dione ( 29 ). Aspochalasin D ( 1 ) is a diastereomer of aspochalasin C (different configuration at C (17) or C (18)).