Electrochemical Induced Remote C(sp)~3-H Thiocyanation

Thiocyanates not only widely exist in natural products and bioactive compounds,but also serve as important intermediates in organic synthesis,which could be easily converted into various sulfur-containing derivatives.Nitrogen radical mediated 1,5-hydrogen atom migration（HAT）strategy has been reported to construct remote C（sp³）-H thiocyanation.These methods not only require pre-functionalization,but also require the use of transition metal catalysts,which are not in line with the concept of green chemistry.There is an urgent need to develop a green and efficient new method to achieve remote C（sp³）-H thiocyanation.Organic electrochemical synthesis,using electrons as traceless redox reagents,could avoid the use of toxic redox agents,and reduce the generation of by-products,It has become a hot field in organic synthesis.In this paper,a new method for constructing remote C（sp³）-H thiocyanation using an electrically induced nitrogen-centred radicals mediated 1,5-HAT strategy has been established.This method does not require pre-functionalization,and generates nitrogen radicals by directly breaking the N-H bond.Carbon radicals are generated through 1,5-HAT process,which are coupled with thiocyano radical to obtain distal C（sp³）-H thiocyano products.The optimal reaction conditions were determined through screening nearly 100conditions,and 21 thiocyanates with different functional groups such as electron rich,electron deficient,and halogen were successfully synthesized.Primary,secondary,and tertiary carbon substrates can react smoothly.The direct late-stage thiocyanation of bioactive molecules was also achieved.This method requires no oxidant,and has good functional group tolerance and high selectivity.All the products in this article were characterized by ¹H NMR and ¹³C NMR to determine their structures.The possible mechanism of this reaction was proposed through radical capture experiments,nuclear magnetic resonance experiments and cyclic voltammetry experiments.