The Chemistry of α,β-Ditosyloxy Ketones: Hypervalent Iodine (III) Mediated Synthesis of Alkynes from α, β-Unsaturated Carbonyl Compounds Containing Pyrazole Moiety

Background: The present study is an effort to extend the utility of the alpha,beta-ditosyloxy chalcone derivatives in establishing the reaction patterns of these compounds which at once was thought that they might behave similar to alpha,beta-dibromo ketones but the results obtained were quite different and interesting in nature. Methods: In the present methodology, the alpha,beta-chalcone ditosylates containing pyrazoles were prepared from corresponding chalcone derivatives on treatment with [hydroxyl(tosyloxy) iodo] benzene in dichloromethane at room temperature and that were further allowed to react with potassium hydroxide in methanol. Results: A new series of acetylenic ketones were obtained in the present case in excellent yield. The analytical data of the compounds fully satisfy the structures of the compounds. Conclusions: In the present case, the alpha,beta-chalcone ditosylates lead to the elimination of ditosyloxy groups and the products isolated are acetylenic ketones which are stable under the reaction conditions. Hence, it offers a facile and convenient route for the synthesis of acetylenic ketones which are difficult to synthesize otherwise.