Enantioselective Wittig Reactions Controlled by PIII/PV=O Redox Catalysis

Abstract The development of catalytic PIII/PV=O redox processes has transformed the Wittig reaction, traditionally plagued by stoichiometric phosphine oxide byproducts, into an efficient and more benign method for synthesizing alkenes. Recently, the feasibility of enantioselective PIII/PV=O redox catalysis was demonstrated by using chiral phosphine catalysts, such as HypPhos. For example, an atroposelective Wittig reaction using Boc-MBH adducts, where endogenous base release facilitates ylide formation and acid co-catalysis, allows enantiocontrol and effective PIII/PV=O redox cycling, while catalyst-stereocontrolled enantioselective Wittig reactions generally extend the scope and sustainability of the synthesis of complex molecules. 1 Introduction 2 meso-Desymmetrizations 3 Atroposelective Catalysis 4 Conclusion