Direct Sulfanylation Of 4-Hydroxycoumarins With Thiols In Water For Synthesis Of 4-sulfanylcoumarins

As a privileged scaffold, coumarin shows interesting biological properties. The prominence of coumarin in natural products and biologically active molecules has promoted considerable efforts toward their synthesis. Recently, it was found that 4-sulfanylcoumarins showed promising anti-HIV activities,anti-bacterium activities, anti-oxidation activities, and anti-bone fracture rarefaction activities. The discovery warranted the development of efficient and rapid syntheses and evaluations of analogous structures in the search for better inhibitors. Although 4-sulfanylcoumarins have been synthesized either for biological evaluation or as key intermediates in generation of complex molecules, their syntheses usually suffer from multiple synthetic steps, harsh reaction conditions and poor substituent tolerance. Thus, it is highly desired to develop general and efficient methods for the synthesis of 4-sulfanylcoumarins, especially in a green process.In this paper, we described a green, efficient, and novel route for the synthesis of 4-sulfanylcouamrins via direct sulfanylation of 4-hydroxycoumarins with thiols. 4-Hydroxycoumarin was utilized as starting material for synthesis of 4-sulfanylcoumarins in the presence of p-toluenesulfonyl chloride as C-OH bond activator. This transformation is highly effective which is performed in water at room temperature under air atmosphere. The efficiency of this method combined with the operational simplicity of the present green process makes it potential attractive for library construction...