Formal Total Synthesis of (±)-Pseudomonic Acids A and C. The Quasi-Intramolecular Lewis Acid Catalyzed Diels-Alder Reaction

Abstract

A formal total synthesis of pseudomonic acid A (1) has been achieved by using an ene reaction in sequence with a quasi-intramolecular Lewis acid catalyzed Diels-Alder reaction, which converts 19 to 24, as the key step. “Quasi-intramolecular” refers to a Diels-Alder reaction in which the Lewis acid binds covalently to the diene and complexes to the dienophile, providing the regiochemical control typical of intramolecular Diels-Alder reactions and the acceleration typical of Lewis acid catalysis. The scope and mechanism of this reaction are explored as well as its potential for control of endo-exo stereochemistry and stereochemistry on a side chain. © 1983, American Chemical Society. All rights reserved.