Convergent synthesis of the spiroketal core of the HIV-1 protease inhibitors the didemnaketals

Abstract

A stereocontrolled and efficient synthetic approach to the spiroketal compound 4a and its C1″-epimer 4b, the core of the HIV-protease inhibitor didemnaketals isolated from the ascidian Didemnum sp., is developed through a multi-step approach from natural L-(−)-menthone. This route involves the highly diastereoselective construction of four chiral carbon centers by intramolecular chiral induction.