Anthranil: An Aminating Reagent Leading to Bifunctionality for Both C(sp³)−H and C(sp²)−H under Rhodium(III) Catalysis

Abstract

Previous direct C-H nitrogenation suffered from simple amidation/amination with limited atom-economy and is mostly limited to C(sp(2) )-H substrates. In this work, anthranil was designed as a novel bifunctional aminating reagent for both C(sp(2) )-H and C(sp(3) )-H bonds under rhodium(III) catalysis, thus affording a nucleophilic aniline tethered to an electrophilic carbonyl. A tridendate rhodium(III) complex has been isolated as the resting state of the catalyst, and DFT studies established the intermediacy of a nitrene species.

Rhodium‐Catalyzed Amination and Annulation of Arenes with Anthranils: C‐H Activation Assisted by Weakly Coordinating Amides

“…These methods required functionalized aromatic starting materials or harsh conditions which delivered products with limited atom-economy. [11][12][13][14][15][16] While the strategy of CÀH amination is appealing, it is desirable to introduce two functional groups in one single transformation. Two classes of amination reactions have been developed using nucleophilic or electrophilic aminating reagents.…”

“…With the increasing interest of CÀH activation chemistry, transition metal catalyzed CÀH amination/amidation [4] has been increasingly explored using palladium, [5] rhodium, [6] ruthenium, [7] iridium, [8] cobalt, [9] and copper [10] catalysts. [14,17] In the cases when highly nucleophilic arene substrates such as indoles were used, further cyclization to acridines may arise due to the nucleophilic nature of the aniline intermediate and the electrophilicity of the resulting proximal carbonyl group. The electrophilic aminating reagents are particularly attractive owing to high reactivity and redox-neutrality ( Figure 1).…”

“…The electrophilic aminating reagents are particularly attractive owing to high reactivity and redox-neutrality ( Figure 1). [14,17] Applications of weak oxygen chelators [18] in amination have been rare in general, and secondary amides were mostly employed. Ideally, this is realized by scission of an NÀE bond of a ring (E=N, O, or C) and both the N and the E atoms are incorporated into the product, leading to bifunctionality.…”

“…In this context, we and others independently applied anthranils as an aminating reagent for both sp 2 and sp 3 CÀH bonds under chelation assistance. Switch of the additive to zinc acetate raised the yield to 86% (entry 9), while other Zn(II) salts or metal acetates all resulted in lower yields (entry [10][11][12][13][14][15][16], indicating that both the cation and anion of Zn(OAc) 2 played an important role. [17a,b] Despite the progress, the directing group of such systems have been strictly limited to strong nitrogen chelators.…”

Rhodium‐Catalyzed Cyclization of O,ω‐Unsaturated Alkoxyamines: Formation of Oxygen‐Containing Heterocycles

“…[1] Among the different metal catalysts used in C À Ha ctivations,r hodium-(III) [2] has been extensively studied and anumber of rhodium-(III)-catalyzed C(sp 2 ) À H, [3,4] as well as C(sp 3 ) À H [5] bond activations have been reported. In this context, CÀHactivation has become avery powerful method for functionalizing ad iversity of molecules.…”