Ruthenium-Catalyzed Chemoselective N–H Bond Insertion Reactions of 2-Pyridones/7-Azaindoles with Sulfoxonium Ylides
作者:Xiaofeng Liu、Ying Shao、Jiangtao Sun
DOI:10.1021/acs.orglett.0c04229
日期:2021.2.5
excellent N-selectivity. The key to achieve this unprecedented N–H rather than O–H insertionreaction is the use of CpRu(PPh3)2Cl as the catalyst and sulfoxoniumylides as the alkylation reagents. Moreover, this protocol is also amenable to 7-azaindoles by slightly varying the reaction conditions. Furthermore, sulfonium ylides are also suitable alkylation reagents, providing the N-alkylated 2-pyridones in
oxazolo[3,2-a]pyridines III were obtained via tandem ring opening and ringclosure from stable mesoionic 3-acyloxazolo[3,2-a]pyridinium-2-olates I. The key intermediates of this tandem transformation are N-(b-oxoethyl)pyridones-2 II obtained by Dakin-West acylation of (pyridone-2-yl-1)acetic acid. An example of further utilization of this strategy is illustrated by preparation of unknown 2-benzylimidazo[1