Rhodium-catalysed decarbonylative C(sp²)–H alkylation of indolines with alkyl carboxylic acids and carboxylic anhydrides under redox-neutral conditions

Abstract

We developed a rhodium-catalysed decarbonylative C(sp2)–H alkylation method for indolines. This reaction facilitates the use of alkyl carboxylic acids and their anhydrides as a cheap, abundant, and non-toxic alkyl source...

Rhodium-Catalyzed Decarbonylative Intramolecular Arylation of 2-(1H-Indole-1-carbonyl)benzoic Acids

“…In our recent work, we developed a rhodium-catalyzed decarbonylative C(sp 2 )–H alkylation of indolines with in situ formed mixed anhydrides (Scheme 1 B). 10c In line with our ongoing interest in rhodium-catalyzed C(sp 2 )–H activation using anhydrides, 10 we focused on investigating a novel decarbonylative intramolecular arylation. This process is applied to 2-(1 H -indole-1-carbonyl)benzoic acids, which are synthesized from an indole and phthalic anhydride in a single step, making the isoindoloindolone synthesis more concise and efficient (Scheme 1 C).…”

Rhodium-Catalyzed Intramolecular Acylation of 2-(Indol-1-yl)-benzoic Acids under Redox-Neutral Conditions

“…On the basis of our previous work on the rhodium-catalyzed redox-neutral alkylation of indolines, 8c we commenced our study by examining intramolecular acylation of 2-(indol-1-yl)benzoic acid ( 1a ) with pivalic anhydride (Piv 2 O, 1.5 equiv) and [RhCl(CO) 2 ] 2 (5.0 mol%) in 1,4-dioxane at 150 °C for 18 h. The desired 10 H -indolo[1,2- a ]indol-10-one ( 2a ) was obtained in 28%, along with a C3-acylated indoloindolone via an intermolecular acylation of 2a with Piv 2 O (Table 1 , entry 1). The addition of KI (30 mol%) suppressed the over-acylation of 2a , resulting in a higher yield of the desired product (entry 2).…”

Rh(III)‐Catalyzed Direct ortho Alkylation of Carbazoles with Nitroalkenes

“…Two N ‐pyrimidinyl carbazoles were well tolerated to afford C1 and C8 dimethylated products [10a] . Recently, Matsuda demonstrated an example of decarbonylative C1‐alkylation of N ‐pyrimidinyl carbazole with 3‐phenylpropionic acid under rhodium catalysis [10b] . Beyond these few examples, the ortho ‐C–H alkylation of carbazoles needs for further research, specifically, both the substrate scope around the carbazole core and the related mechanism require in‐depth study.…”