Synthesis of Coronafacic Acid via TBAF-Assisted Elimination of the Mesylate and Its Conversion to the Isoleucine Conjugate

An aldol reaction followed by elimination of the derived mesylate was used to construct the side chain that was designed to afford the cyclohexene ring of coronafacic acid via intramolecular alkylation. Elimination of the mesylate proceeded with TBAF. The alkylation was achieved with t-BuOK in THF, and then hydrolysis afforded coronafacic acid, which upon condensation with unprotected l-isoleucine using ClCO2Bu i furnished coronafacoyl-l-isoleucine, the l-Ile conjugate.