Catalytic Enantioselective Dihalogenation of Alkenes

Abstract Vicinal dihalides not only emerge as reactive intermediates in synthetic organic chemistry, but also are extensively existing in bioactive marine natural products. The dihalogenation of alkenes is the most direct and effective method for the synthesis of vicinal dihalides. Because there is always an exchange process between the chiral haloniums and the unreacted olefins to cause racemization, the development of catalytic enantioselective dihalogenation of alkenes is of great difficulty. Recently, great progress has been made in catalytic asymmetric manner. However, there is a lack of related review of discussions of the mechanisms and reaction systems. This review is aimed at summarizing enantioselective dihalogenation of alkenes, including 1,2-dichlorination, 1,2-dibromination, and 1,2-difluorination, which is expected to encourage more researchers to participate in this field. 1 Introduction 2 Enantioselective 1,2-Dichlorination and 1,2-Dibromination of Alkenes 2.1 Chiral-Boron-Complex-Promoted Enantioselective 1,2-Dichlorination 2.2 Organocatalytic Asymmetric 1,2-Dichlorination and 1,2-Dibromination 2.3 Chiral-Titanium-Complex-Catalyzed 1,2-Dihalogenation 3 Chiral-Iodide-Catalyzed Enantioselective Oxidative 1,2-Difluorination 4 Summary and Outlook