In ynamines the amine N-atom is directly coordinated with C-atom of the alkyne. Due to the presence of adjacent electron donating nitrogen the alkyne triple bond is polarized, which leads the reactivity of ynamines or ynamides. S. Stahl et al., Evano et al. reported copper catalyzed amidation of alkyne and dibromo-alkene to make ynamide respectively. Brown et al. reported N-ethynylpyrazoles synthesis methodology from the 1-alkynyol-3-methylpyrazole precursor by flash vacuum photolysis technique. Burley et al. first reported Cu-catalyzed N-alkynylation of imidazoles, benzimidazoles, indazoles, pyrazoles with bromoalkyne under microwave condition. Copper acetate monohydrate as an active catalyst for regio-selective N-alkynylation of unsymmetrically substituted pyrazoles is reported here from the reaction of unsymmetrically substituted pyrazoles with aromatic and aliphatic terminal alkynes under aerobic condition having moderate to good yield. The single crystal XRD structures of the N-substituted pyrazoles confirm the regioselective connectivity of alkyne C atom with the N1 center of the heterocyclic ring. The cytotoxicity towards MDA-MB 231 breast cancer cells of three of the alkynyl pyrazoles has been investigated.

Copper catalyzed regioselective N – alkynylation of pyrazoles and anticancer activity of ethynyl- pyrazoles

2019 Spring National Meeting

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