Cu-Catalyzed Direct C7 Sulfonylation Of Indolines

Sulfones,as a kind of important sulfur compounds,have found diverse applications in organic synthesis,agriculture and pharmaceutical field.Especially aryl sulfones exhibit antibacterial,anti prostate cancer and other pharmacological properties.Herein,an efficient Cu-catalyzed direct sulfonylation of indolines with easily accessible sulfonyl chlorides has been disclosed under air atmosphere via chelation-assisted strategy.This reaction utilized indolines as the reaction substrate,sulfonyl chlorides as the sulfonyl source,copper(II)acetate mono hydrate as the catalyst,silver carbonate as the oxidant,sodium carbonate as the base,and 1,1,1,3,3,3-Hexafluoroisopropanol(HFIP)as the solvent to access one pot syntheses of C7 sulfonylated indolines,which showed unique features,including broad substrate scope,good functional group tolerance and operational convenience.The main research contents are as follows:N-(Pyrimidin-2-yl)indoline and p-toluenesulfonyl chloride were employed as the model substrates to optimize reaction conditions for sulfonylation of indolines.Under the optimal conditions,a wide range of substituted N-(Pyrimidin-2-yl)indolines and sulfonyl chlorides were well tolerated to afford the corresponding products in up to 83% yield(Scheme 1).Based on a series of control experiments and free radical capture experiments,it was speculated that sulfonyl radical might be involved in this transformation and a possible reaction mechanism was proposed..