Preparation of oxonanes and azonanes by oxidative ring expansion: synthesis of obtusan
Abstract
Oxonanes can be readily prepared from phthalans by a 3-step procedure involving Birch reduction, selective hydrogenation and oxidation. 2-Ethyl-9-pentyloxonane-3,8-dione has been deoxygenated to give obtusan. The method has been applied to the synthesis of an azonane.