Asymmetric Protonation of Carbanions and Polar Double Bonds: Application to Total Syntheses

Abstract

This chapter covers asymmetric protonation methodologies and their applications to total synthesis of bioactive and natural products. The asymmetric protonation of carbanions, α‐stabilized carbanions (metal and silicon enolates), as well as asymmetric protonation of polar double bonds (ketenes and Michael acceptors) are disclosed. A strong emphasis is placed on their synthetic applications toward total synthesis of natural and pharmacologically active products. The aim of this chapter is to summarize what has been done in the field and to highlight the asymmetric protonation as a useful synthetic tool.

Enantioselective Protonation of Enol Esters with Bifunctional Phosphonium/Thiourea Catalysts

“…Enantioselective protonation (EP) is a straightforward and fundamental reaction to construct chiral tertiary carbon centers, which are found in numerous biologically active molecules . However, controlling the enantioselectivity of EP is difficult because a proton is the smallest electrophile in organic synthesis and rapid proton exchange decreases the optical purity of the products.…”