Recent Advances in Copper-Catalyzed Asymmetric Hydroboration of Electron-Deficient Alkenes: Methodologies and Mechanism

Abstract

The efficient synthesis of enantioenriched organoboron compounds has been recognized as an important topic in recent years. As an update review, this article aims to select key achievements in copper-catalyzed, electron-deficient alkene enantioselective hydroboration methodologies since the beginning of 2017. In addition, it covers relevant mechanistic investigations developed over the last six years, as well as total synthesis applications for preparing 1,3-diols as important medicinal intermediates.

1 Introduction

2 Methodologies for Copper-Catalyzed Hydroboration

2.1 α,β-Unsaturated Ketones and Imines

2.2 α,β-Unsaturated Esters and Cyanides

2.3 Aryl Alkenes and Alkyl Alkenes

3 Mechanistic Investigations on the Copper-Catalyzed Hydroboration

3.1 A Cu–BX₂ Intermediate

3.1.1 Experimental Analysis

3.1.2 Borylative Difunctionalization Methodologies

3.1.3 Density Functional Theory

3.2 A Cu–H Intermediate

3.3 Other Mechanistic Proposals

4 Synthetic Applications: Chiral 1,3-Diols

5 Conclusions and Outlook

Key words

alkenes - copper catalysis - hydroboration - asymmetric - mechanism - 1,3-diols - total synthesis

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