Chapter 9 - Pericyclic reactions 2: Asymmetric synthesis

Abstract

This chapter describes asymmetric methodologies involving pericyclic reactions. Asymmetric approaches to Diels–Alder reactions based on chiral diene substrates, chiral auxiliaries, chiral catalysts and organocatalysis are presented with synthetic applications. A simple mnemonic for the asymmetric Diels–Alder reaction is provided to delineate the absolute stereochemistry of endo product. Asymmetric 1,3-dipolar cycloadditions are described using chiral substrates, chiral auxiliaries, chiral catalysts and organocatalysis. Asymmetric cyclopropanation particularly based on Charette dioxaborolane auxiliary and asymmetric catalysis using chiral copper and rhodium complexes is presented. Two main asymmetric approaches to ene reactions involving chiral auxiliaries and chiral titanium-BINOL and copper-box catalysts are provided. Asymmetric Claisen rearrangements are described using substrate control including enantioconvergent synthesis, auxiliary control, reagent control using a chiral boron reagent and asymmetric catalysis including Pd catalysis of Overman imidate–amide rearrangement. Asymmetric Wittig rearrangements are presented using substrate control, chiral auxiliary strategy and asymmetric catalysis based on phase-transfer catalysis and synergistic ion-binding catalysis.