Recent Advances in Stereoselective Syntheses Using N-Acylimines

Abstract: The electron-withdrawing aptitude displayed by the acyl group makes N-acylamines very attractive substrates in many processes aimed at the preparation of amino derivatives. The remarkable electrophilicity of N-acylimines can be profitably used to overcome reactivity troubles often observed using N-alkylimines and N-arylimines. The presence of a polar acyl moiety on the nitrogen atom is particularly effective in stereoselective reactions were electrostatic interactions play a major role in determining the facial preference for the nucleophilic attack. Utilization of alkoxycarbonyl groups (e.g. Boc or Cbz) as activating N-acyl substituents allows one to obtain the final amino derivative in a protected form that can be readily cleaved under mild conditions. In this review, several synthetic applications of N-acylimines in stereoselective reactions that have appeared in the literature since 1990 are discussed. 1 Introduction 2 Preparation of N-Acylimines 3 Nucleophilic Additions to N-Acylimines 3.1 Reaction with Organometallic Reagents and Related Carbanions 3.1.1 Linear N-Acylimines 3.1.2 Cyclic N-Acylimines 3.2 Reaction with Enolate Anions 3.2.1 Nitroalkanes: The Aza-Henry Reaction 3.2.2 1,3-Dicarbonyls 3.2.3 Carbonyls and Related Derivatives 3.2.4 Carboxylic Acid Derivatives 3.3 Reaction with Aromatic Compounds 3.4 Reaction with Heteronucleophiles 4 Cycloaddition Reactions 5 Conclusion