Ring Expansion from 16-Membered Macrocyclic Lactones Using Yamaguchi and Photoinduced Decarboxylative Radical Macrolactonization

Abstract

This study describes a new strategy for synthesizing 31-, 33-, 46-, and 48-membered macrocyclic lactones from commercially available 16-membered macrocyclic lactones using the Yamaguchi reaction and photoinduced decarboxylative radical macrolactonization. Despite challenges with the low solubility of substrates and the slow rate of photochemical radical cyclization, the preparation of enlarged macrocyclic lactones from 16-membered macrocyclic lactones was successfully accomplished. Additionally, the effect of the Lewis acidity of the counter cation in the carboxylate salt provided mechanistic insights into the photoinduced decarboxylative radical macrolactonization.