Vsible Light-promoted Cyclization Of 1,6-Enynes With Benzenesulfonic Acid Dithioester Reagent

Disulfide bond is a significant organic functional group and plays a key role in different types of organic molecules.For example,they can not only act as bridges,adding additional stability to the protein’s 3D structure required for protein folding and function,but also link different DNA fragments.In addition,due to their unique functions and odors,disulfide compounds enjoy a special status in fields such as dr ug discovery,food processing,energy materials and the like.Therefore,it is of great significance to realize the construction of S-S bonds and develop a method for the efficient synthesis of disulfide compounds.The synthetic methods of classical disulfide compounds are mainly based on thiols,including oxidative coupling between two different thiols and thiol-based nucleophilic substitution reactions.However,considering that thiol itself has a foul odor,and this process cannot avoid the formation of self-coupling products,the development of green and efficient methods for synthesizing disulfide compounds has become a research hotspot for scientists.In recent years,organic chemists have developed novel disulfide reagents such as Fm-SSR,Phth N-SSR,Ac-SSR,RSS-SSR,Me O-SSR,Ts-SSR,and a series of new methods for asymmetric disulfide compounds have been reported based on cross-coupling,nucleophilic substitution,and radical substitution processes.While,the above reaction process also has the limitation of its low atom economy.On the other hand,with the renaissance of free radical chemistry,1,6-enynes are also gaining popularity as good radical acceptors.Up to date,scientists have successfully introduced various functional groups into 1,6-enynes and synthesized highly functionalized five-membered ring compounds.Along these lines,the author combined organosulfur chemistry and radical chemistry,selected 1,6-enynes as free radical acceptors,benzenesulfonic acid dithioester reagents as disulfide reagents,and developed a visible light-induced redox strategy.A green,economical and efficient method for the synthesis of disulfide-substituted pyrroles by radical cyclization w as developed.The reaction generated three new bonds,namely,C–SO₂,C–C,and C–SSR under extremely mild conditions.Through the screening of photocatalysts,additives,solvents,1,6-enyne substrates and disulfide reagent equivalents,the authors determine d the optimal reaction conditions to obtain the desired product in 83%yield,and the structure of the product was further identified by X-ray single crystal diffraction.Besides,the authors used this reaction condition for substrate expansion to synthesize a series of disulfide-substituted pyrrole compounds.The results showed that this reaction is suitable for 1,6-enynes and benzenesulfonic acid dithioester reagents with various substituents.It shows that the reaction has high universality and good comp atibility.Moreover,we successfully achieved gram-scale synthesis reactions and subsequent derivatization studies by this method,which indicated that this method ha d high practical value and application potential.