At outset, we commenced our study with ynone 1a and thiosulfonate 2a as the model substrates. To our delight, in the presence of 10 mol% DBU, the vicinal thiosulfonylation reaction proceeded smoothly in THF at room temperature to produce the desired product 3a in 87% yield (Table ). Encouraged by this success, several other common bases were then examined. TBD and DBN catalyzed the difunctionalization in high yield (Table and). Triethylamine, the Hunig's base, DABCO and Ph 3 P cannot catalyze the reaction ( Finally, the control experiment showed that in the absence of a base, no desired product was formed (Table , entry 21). With the optimal reaction conditions in hand, we first examined the substrate scope of ynones, with the results summarized in Table . A variety of ynones with substituents on the aromatic rings underwent the thiosulfonylation efficiently to give the desired vinyl sulfones in high yield and excellent regio-and stereoselectivity (3a-3q). In addition, different positions and electronic properties have no apparent impact on the reaction yield and selectivity (3r-3x). The bulky naphthyl derived ynones 1y and 1z participated in the reaction to afford the corresponding products 3y and 3z in 98% and 88% yields, respectively. Heteroaryl substituted ynones were proven to be very good reactants for the reaction, furnishing the corresponding produces in excellent yield (3aa-3ac). Gratifyingly, different alkyl-substituted ynones also performed very well, giving the desired products in high yield and excellent E-selectivity (3ad-3ai). We next investigated the substrate scope of thiosulfonates in this transformation. Both symmetrical and unsymmetrical thiosulfonates smoothly underwent the reaction, affording the corresponding thiofunctionalized vinylsulfones in high yields and excellent regioselectivity (Table ). Substrates bearing electron-donating, -withdrawing and neutralsubstituents coupled with ynones to produce the desired products in excellent yields (3aj-3ap). Different positions of the substituents have no obvious influence on the reaction yield and selectivity (3aq-3as). The bulky naphthyl-derived thiosulfonate 2l reacted efficiently with ynone 1x to furnish 3at in high yield. Heteroaryl-derived thiosulfonate 2m