Recent advances in directed C–H functionalizations using monodentate nitrogen-based directing groups

Abstract

The use of directing groups has proven to be a successful strategy to enhance reactivity and control selectivity in C-H functionalization reactions. In the past decade, a multitude of new transformations and new directing groups have been explored, and several recent reviews have discussed directing group approaches for C-H functionalization. This review focuses specifically on the use of monodentate nitrogen-based directing groups published during the past two years, with the aim of covering a body of literature that is complementary to existing reviews.

Ru-catalysed C–H silylation of unprotected gramines, tryptamines and their congeners

“…N-methyl, N-tosyl and N-(2-pyrimidyl) indoles gave no conversion (8a-c); N-acetyl and NBoc indoles gave complex mixtures (8c-d). Silylation at C2 therefore proceeded most efficiently with unconjugated, strong σ-donor DGs, 20 which presumably favours an oxidative addition by Ru species into the C-H bond. The scope was expanded to a range of gramine derivatives (2j-p), although nitro and ester substituents (2q,r) shut down the reaction (Scheme 2B).…”

Selective C(sp3)−H and C(sp2)−H Fluorination of Alcohols Using Practical Auxiliaries

“…[13] Thed esign of novel directing groups enriches the scope of CÀHfunctionalization by improving the reactivity as well as selectivity.F or instance, the hydroxy group itself as an O-donor ligand directing group was less efficient because of its weak coordinating ability to the transition metal, thus novel strategies using masked alcohols as auxiliaries were developed for the CÀHb ond functionalization of alcohols. [13] Thed esign of novel directing groups enriches the scope of CÀHfunctionalization by improving the reactivity as well as selectivity.F or instance, the hydroxy group itself as an O-donor ligand directing group was less efficient because of its weak coordinating ability to the transition metal, thus novel strategies using masked alcohols as auxiliaries were developed for the CÀHb ond functionalization of alcohols.…”

Ruthenium-Catalyzed C–H Arylation of Diverse Aryl Carboxylic Acids with Aryl and Heteroaryl Halides

“…This opens up opportunities for sequential, orthogonal functionalization since the amide group is a powerful directing group in combination with various metal catalysts. 2,9g,9k …”