Verma Suryadev K, Punji Benudhar
Organometallic Synthesis and Catalysis Group, Organic Chemistry Division, CSIR-National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha Road, Pune, 411 008, India.
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002, India.
Chem Asian J. 2022 May 2;17(9):e202200103. doi: 10.1002/asia.202200103. Epub 2022 Apr 1.
Selective C(sp )-H bond alkylation of indoline, carbazole and (2-pyridinyl)arenes with unactivated alkyl bromides is achieved using MnBr catalyst in the absence of an external ligand. The alkylation uses a simple LiHMDS base and avoids the necessity of Grignard reagent, unlike other Mn-catalyzed C-H functionalization. This reaction proceeded either through a five- or a less-favored six-membered metallacycle, and tolerated diverse functionalities, including alkenyl, alkynyl, silyl, aryl ether, pyrrolyl, indolyl, carbazolyl and alkyl bearing fatty alcohol and polycyclic-steroid moieties. Alkylation follows a single electron transfer (SET) pathway involving 1e oxidative addition of alkyl bromide and a rate-limiting C-H metalation.
在没有外部配体的情况下，使用溴化锰催化剂实现了吲哚啉、咔唑和（2-吡啶基）芳烃与未活化的烷基溴的选择性C(sp³)-H键烷基化反应。与其他锰催化的C-H官能化反应不同，该烷基化反应使用简单的六甲基二硅基胺基锂碱，避免了使用格氏试剂的必要性。该反应通过五元或不太有利的六元金属环进行，并能耐受多种官能团，包括烯基、炔基、硅基、芳基醚、吡咯基、吲哚基、咔唑基以及带有脂肪醇和多环甾体部分的烷基。烷基化反应遵循单电子转移（SET）途径，涉及烷基溴的1e氧化加成和限速的C-H金属化反应。
