Electrochemically driven hydrogen atom transfer (HAT)
catalysis
provides a complementary approach for the transformation of redox-inactive
substrates that would be inaccessible to conventional electron transfer
(ET) catalysis. Moreover, electrochemically driven HAT catalysis could
promote organic transformations with either hydrogen atom abstraction
or donation as the key step. It provides a versatile and effective
tool for the direct functionalization of C(sp3)–H/Si–H
bonds and the hydrofunctionalization of alkenes. Despite these attractive
properties, electrochemically driven HAT catalysis has been largely
overlooked due to the lack of understanding of both the catalytic
mechanism and how catalyst selection should occur. In this Review,
we give an overview of the HAT catalysis applications in the direct
C(sp3)–H/Si–H functionalization and hydrofunctionalization
of alkenes. The mechanistic pathways, physical properties of the HAT
mediators, and state-of-the-art examples are described and discussed.