C-H Bond Silylation of Heteroarenes

Organosilicon compounds are highly important molecular scaffolds with versatile synthetic utility, and are used in a range of transformations. Such organosilicon compounds are employed in a wide range of research areas, including medicinal chemistry, drug discovery, pharmaceuticals, agrochemicals, fine chemicals, etc. Moreover, they are commonly encountered in a number of commercial products. However, the preparation of organosilicon compounds by means of traditional methods significantly limit their wider applications. Recently, several new concepts and powerful methods have been developed in order to prepare organosilicon compounds via transition-metal catalysis or without metal catalysis. While many procedures have been reported for the silylation of aromatic systems, methods for the silylation of heteroarenes are scarce. Nevertheless several excellent and robust strategies for heteroarene silylation have been discovered. In this short review, we summarize the different methods, mechanisms and catalyst development for the regioselective silylation of heteroarenes. 1 Introduction 2 Silylation of C-H Bonds through Organometallic Intermediates 2.1 Intermolecular C-H Bond Silylation Assisted by Directing Groups 2.2 Undirected Intermolecular C-H Bond Silylation 2.3 Intramolecular C-H Bond Silylation via a Tethered Silyl Unit 3 C-H Bond Silylation with Silicon Electrophiles 4 C-H Bond Silylation with Silicon Nucleophiles 5 C-H Bond Silylation with Silyl Radicals 6 Other Approaches 6.1 Alkali-Metal-Catalyzed C-H Bond Silylation 6.2 Magnesium-Promoted Reductive C-H Bond Silylation 7 Conclusions and Outlook