Crystal structure and relative configuration of the N-acetyl-γ-lactone of the antifungal antibiotic thermozymocidin

Abstract

An X-ray crystal structure determination of (1), the acetylation product of thermozymocidin [C₂₃H₃₉NO₆, orthorhombic, space group P2₁2₁2₁, a= 41.477(9), b= 10.753(5), c= 5.543(1)Å, Z= 4, direct methods, final R 0.062 for 1 124 independent reflections], has established the relative configuration of the asymmetric carbon atoms of this antifungal antibiotic. The structure analysis shows a large thermal vibration in the long aliphatic chain which can explain the systematic shortening of the observed bond distances. The conformations of the carbon chain and of the lactone ring are discussed.