Total Synthesis of (±)-Atpenin B. An Original “Clockwise” Functionalization of 2-Chloropyridine

Abstract

(-)-Atpenin B (1) is an antibiotic produced by Penicillium sp. FO-125. The first synthesis of 2,4-dihydroxy-5,6-dimethoxy-3-((2RS,4RS)-2,4-dimethyl-1-oxohexyl)pyridine (atpenin B) (16) is reported. This molecule, which exhibits a pentasubstituted pyridine structure, was prepared from 2-chloropyridine in 13 steps, by metalating and then functionalizing, one after another, all the remaining positions of the pyridine ring. The methodology involves four metalation steps (including metalation of 2,3-dimethoxypyridine and pyridyl N,N-diisopropylcarbamates), one halogen-scrambling step, and one bromine-lithium exchange step. © 1994, American Chemical Society. All rights reserved.