Convergent Synthesis of Polyether Ionophore Antibiotics: Protective Manipulation and Synthesis of Monensin A

Abstract

The protective manipulation and synthesis of the polyether antibiotic monensin is described. The hydroxyl groups and the carboxylic acid of monensin are protected, and its spiroketal is equilibrated to provide naturally derived, advanced targets for comparison to the synthetic materials. The total synthesis of these targets from spiroketal acids 3ax and 3eq and tricyclic glycal 4 by a highly convergent ester enolate Claisen rearrangement is described. Finally, the deprotection of each to monensin is described. © 1993, American Chemical Society. All rights reserved.