Synthetic Approaches to Rapamycin: Synthesis of a C10-C26 Fragment via a One-Pot Julia Olefination Reaction

Abstract

Key steps in a synthesis of the C10-C26 fragment of the immunosuppressant Rapamycin include (a) the use of a metallated benzothiazolyl sulfone in a one-pot Julia olefination to create the C21-C22 alkene stereoselectively and (b) a diastereoselective acid-catalysed cyclisation of a hydroxyl function onto a ketenedithioacetal (1,4-asymmetric induction) in order to create the oxane ring and fix the stereochemistry at C11.