Carbon Dioxide-mediated Synthesis Of3(2H)-furanones From Diyne Alcohols

3（2H）-furanones are key structural units in a variety of natural products. In addition,many of the3（2H）-furanones have shown pharmaceutical activities so that they areconsidered to be promising biological and pharmaceutical candidates. Therefore, it is of greatsignificance to develop a simple and efficient method for the synthesis of these compounds.The reaction of propargyl alcohols and carbon dioxide has always been a hot topic aspart of the utilization of carbon dioxide in organic synthesis. In this paper, carbon dioxide-mediated synthesis of3（2H）-furanones from diyne alcohols with and without O₂wasinvestigated for the first time.In the absence of O₂, we found the optimum reaction conditions for the synthesis of3（2H）-furanones as summarized as follows: diyne alcohols （0.25mmol）, H₂O （10eq.）, carbondioxide （2MPa）,90oC,36h, MeCN/Et3N （volume ratio10:1） as the solvent （2mL）. Underthe optimum reaction conditions, the tertiary diyne alcohols could be smoothly converted intothe corresponding products （47%⁸7%yields） and the reactions with secondary diynealcohols gave fairly low yields （23%²5%）.In the presense of O₂, carbon dioxide-mediated one-pot synthesis of5-benzoyl-3（2H）-furanone from diyne alcohols and water was investigated. It was showedthat the5-benzyl-3（2H）-furanone product could be oxidized into5-benzoyl-3（2H）-furanoneusing O₂as the sole oxidant, and the optimum reaction conditions of one-pot synthesis of5-benzoyl-3（2H）-furanone from diyne alcohols and water was summarized as followed: diynealcohols （0.25mmol）, H₂O （10eq.）, carbon dioxide （2MPa）,90oC, O₂（0.6MPa）,48h,MeCN/Et3N （volume ratio10:1） as the solvent （2mL）. Under these conditions, the tertiarydiyne alcohols could also be smoothly converted into the corresponding products in goodyields （50%⁸3%）.In addition, the reaction mechanism was further studied and a possible mechanism wasproposed. Our work showed that carbon dioxide could not only react with propargyl alcoholsto afford cyclic carbonates, but also mediate diyne alcohols to afford3（2H）-furanones. Wedeveloped a simple and efficient method for the synthesis of3（2H）-furanones, and also madecontribution to the carbon dioxide-mediated reactions.