Synthese makrocyclischer, $\alpha, \beta$-ungesättigter y-Oxolactone durch Ringerweiterungsreaktionen; ein neuer Weg zum makrocyclischen Lacton-Antibiotikum A 26771 B

Abstract

A new synthetic route to the a$- unsaturated y-oxolactones 2a and 2b, involving two ring-enlargement reactions, is described. Ring opening of bicyclic a- nitroketones of the type 3 gave ring-enlarged compounds of the type 4 which were converted to monoprotected diketones of the type 10 by using a variation of the Nefreaction as a key step. Macrocyclic lactones of the type I1 were obtained by Baeyer-Viffiger oxidation and converted into compounds of the type 2. The conversion of 2b to the macrocyclic lactone antibiotic A 26 771 B (1) is already described in the literature.