Novobiocin II. Die Synthese der 3–O–Carbamoyl‐noviose

Abstract

Abstract The synthesis of 3‐O‐carbamoyl‐noviose, the carbohydrate of the antibiotic novobiocin, is described. Starting with D ‐glucose the synthesis comprises a number of steps ( 1 – 5 ) up to the important intermediate 3,5,6‐tri‐O‐benzyl‐2‐O‐methyl‐ D ‐galactono‐γ‐lactone (5), which was obtained by an intramolecular WALDEN inversion of 3,5,6‐tri‐O‐benzyl‐4‐O‐mesyl‐2‐O‐methyl‐ D ‐glucono‐N‐methylamide ( 4 ). Compound 5 shows the correct steric arrangement of the asymmetric centres with respect to noviose. Successive transformations ( 6 – 10 ) led to the synthesis of noviose and finally ( 9 – 14 ) to methyl 3‐O‐carbamoyl‐α‐novioside, which was identical with the substance obtained by acid catalysed methanolysis of the antibiotic novobiocin.