Pd(Ⅱ)-catalyzed Nitration Of Unactivated C(sp~3)–H Bonds

Nitro compounds are important in organic chemistry.They are an important part of natural products,medicines,pesticides,spices,explosives,dyes and other substances.Introducing different amounts and kinds of functional groups into aromatic and heterocyclic systems can improve the application of them.Transition metal-catalyzed C-H activation is the most commonly used method to realize C-H functionalization,These methods have high yield and good regioselectivity.Based on the previous nitration conditions,this paper attempts to explore the best conditions of C-H nitration.Indeed,the desired product is obtained in 54%yield,with ketone modified by directing group as substrate,alladium acetate as catalyst,tert-butyl nitrite as nitrating agent,benzoic acid as additive,and acetonitrile as solventWith the optimum reaction conditions in hand,various substances were investigated successively.Both aromatic ketones and alkyl ketones are better compatible under the standard conditions,compared to other’s studies,this is the expansion and progress of nitration.Finally,nitro products are completed,providing moderate to good yields,with the analysis data of¹H NMR,¹³C NMR and HRMS.In order to explore the reaction mechanism,control experiments were carried out.On the basis of the results,the previous investigations,a possible mechanism for the nitration is proposed as the reaction involves radical initiation,combining with the activated substrate to afford the product.