New Methods For Preparation Of β-keto Sulfones By Oxidative Radical Rearrangement Reaction

β-Keto sulfones are common component of drug and widely exist in the natural product structure.In addition,they also play an important role in organic synthesis as necessary intermediates.Therefore,the synthesis of β-keto sulfones has been hot point.There are some defects in literatures about synthesizing β-keto sulfones.For example,required multi-step synthesis of starting materials,relatively complicated and harsh reaction conditions,the use of highly toxic reagents,more undesired by-products or restricted substrate scopes.However,there are few reports on the synthesis of such compounds with vinyl sulfonates compounds as raw materials,and this method was reported has a certain degree of limitation.It is not widely used due to the relative harsh conditions of high temperature(100 ℃ or 140 ℃)or UV light irradiation and limited substrate scope,especially cyclic enol tosylates required even higher temperature.Therefore,to study a more efficient,mild and,especially,sustainable protocol to the preparation of β-keto sulfones has scientific significance in the theoretical research and industrial applications.In this paper,we describe the reaction of vinyl sulfonates to the synthesis ofβ-keto sulfones by rearrangement mechanism under the effect of visible light inducement or radical oxidation.The main contents are as follows:Part one:vinyl sulfonates under the joint effect of organic photocatalyst and visible light produced β-keto sulfones efficiently.With the optimized conditions in hand,we not only expanded the substrate scope and also studied the mechanism of the reaction by a series of mechanistic experiments,such as radical-trapping experiment,calculation of apparent quantum yield and crossover reaction.On the basis of the above experiments and literature survey,a putative set of reaction cycles is depicted.This method has the following advantages:Catalytic amount of organic photocatalyst,wide substrate scope(complex substrate can also be applied in this way),highly atom-economy,easy operation,mild conditions and so on.Part two:vinyl sulfonate produce β-keto sulfones in the under the catalytic oxidation of silver nitrate and ammonium persulfate.Under the optimal reaction condition,we explored the substrate scope and researched the reaction mechanism.This method has the following advantages:catalytic amount of catalyst and oxidant,wide substrate scope and so on.