Transition-metal-free Phenylselenylation Of Arene C-H Bonds With Activated Methyl Phenyl Selenoxide

The direct functionalization of C-H bonds catalyzed by transition metals is an effective way to form carbon-carbon bonds and carbon-heteroatoms bonds.It has been used in the rapid synthesis of biologically active compounds.In the meantime,the functionalization of C-H bonds guided by main group elements is also a chemical reaction process that is worthy of study.It may provide important supplements to the transition metal-catalyzed C-H bonds functionalization and avoid possible problems such as residue of metal catalysts.Selenide are a class of very important organic intermediates.They have a wide range of applications in medicinal chemistry and synthetic chemistry,and exhibit a variety of biological activities,such as anti-tumor,sterilization,pesticides,and so on.Traditional methods for the synthesis of diarylselenides usually involves the reaction between aryl Grignard or aryllithium reagents with electrophilic arylselenium reagents,or alternatively,aryldiazonium salts with nucleophilic arylselenium reagents.Recently,a number of transition-metals have been used to catalyzed the selenylation of C-H bonds.Based on these,we wanted to explore a new method for synthesizing selenide products without using transition metals.Phenylselenylation of arenes were achieved in a one-pot procedure by treating arene substrates with triflic anhydride activated methyl phenyl selenoxide,and then demethylation with diisopropylamine.This reaction provides a convenient method to prepare diarylselenide products under transition-metal-free conditions.The reaction works well in electron-rich arene substrates with up to 94%yield.After that,we tried to developed a novel transition-metal-free,selenium mediated allylic C-H alkylation reaction through a one-pot procedure involving an ene-like step between simple olefins and activated selenoxide,and a subsequent[2,3]-sigmatropic rearrangement step under basic conditions to give allylic C-H alkylation products.Expected product might be conveniently functionalized.But we failed.