Stoffwechselprodukte von Mikroorganismen. 139. Mitteilung. Synthesen in der Sideramin‐Reihe: Rhodotorulasäure und Dimerumsäure

t‐Butyl (E)‐O‐acetyl‐Δ2‐anhydromevalonate could be prepared. by a Reformatsky reaction of 4‐acetoxybutan‐2‐one and t‐butyl bromoacetate. Condensation of its activated derivatives with the diketopiperazine of N5‐hydroxy‐L‐ornithine led to di‐O‐acetyl dimerumic acid, which could be transformed, by ammonolysis, to dimerumic acid, identical with the natural compound. The corresponding acetohydroxamic acid, prepared by acetylation of the diketopiperazine, was identical with natural rhodotorulic acid.