Hypervalent Iodine Reagents Mediated Oxidative C-N Coupling Of Heteroaromatics And Sulfoximines

Arylamines are ubiquitous in a range of biology-oriented aromatics and materials-oriented aromatics.Therefore,the development of efficient and step-economical methods for constructing aromatic carbon-nitrogen（C-N）bonds has been recognized as one of the central issues in synthetic chemistry community for long time.Direct C-H amination is of great importance to supply various amino compounds with high step efficiency and waste-free strategy.In this paper,we have explored the method of constructing C-N bonds of heteroaromatics through C-H functionalization.The main contents are as follows:1.Ph I（OAc）₂-Mediated Oxidative C-H Sulfoximination of ImidazopyridinesTaking 2-phenylimidazo[1,2-a]pyridine and diphenyl sulfoximine as model substrates,the optimized reaction conditions were determined as the combination of 2-phenylimidazo[1,2-a]pyridine（1.5 equiv）,diphenyl sulfoximine（1.0 equiv）,Ph I（OAc）₂（1.2 equiv）in DMSO（1.0 m L）at 30°C for 3 h.The desired C-3sulfoximidoyl-functionalized imidazo[1,2-a]pyridine was obtained in 76%isolated yield.The reaction proceeded smoothly with a wide range of substrates and provided the coupling products in moderate to good yields.Other imidazoheterocycles,such as2-phenylbenzo[d]imidazo[2,1-b]thiazole and 2-（p-tolyl）imidazo[1,2-a]pyrimidine were also compatible to this system.Broad substrate scopes,operational simplicity and mild conditions are the prominent advantages of this methodology（Scheme 1）.2.Ph I（OAc）₂-Mediated Oxidative C-N bond coupling of quinoxalinones and NH-sulfoximinesTaking 1-methylquinoxalin-2（1H）-one and diphenyl sulfoximine as model substrates,the optimized reaction conditions were determined as the combination of 1-methylquinoxalin-2（1H）-one（0.2 mmol）,diphenyl sulfoximine（2.0 equiv）,Ph I（OAc）₂（1.2 equiv）in CH₃CN（0.5 m L）at 60°C for 24 h.The reaction proceeds smoothly under transition metal-free conditions and provides excellent yields of sulfoximidoyl-functionalized quinoxalinone products under mild conditions.This reaction offers a new and convenient strategy to directly install the sulfoximine moiety into the C3position of quinoxalinone（Scheme 2）.