The indole scaffold will continue to play a vital part in the future of drug discovery and agrochemical development. Because of this, the necessity for elegant techniques to enable selective C−H functionalization is vast. Early developments have led to primarily C2 and C3 functionalization because of the inherent reactivity of the pyrrole ring. Despite this, elegant methods have been developed to enable selective C−H functionalization on the benzenoid moiety at C4, C5, C6, and C7. This review focuses on the contributions made in benzenoid C−H functionalization of indoles and other related heteroaromatics such as carbazoles.
Following notable cases of remarkable potency increases in methylated analogues of lead compounds, this review documents the state-of-the-art in C–H methylation technology.
The construction
and manipulation of amine-containing architectures
is of importance to academic and industrial development and discovery
programs. The photochemical single-electron reduction of imine derivatives
to generate α-amino radical intermediates has emerged as a powerful
umpolung strategy for opening up underexplored routes to such amine
motifs. Furthermore, these radicals have been shown to engage in a
wide variety of chemistry, including radical–radical coupling,
addition to electrophiles, and reductive amination chemistry. The
concept has also begun to see application to iminium ion intermediates
and the extension to enantiocontrolled C–C bond formation.
This Perspective covers recent efforts in this synthetic strategy
to simple and complex amine structures alike.
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