Functionalized buta-1,3-diynyl-N-methylpyrazoles by sequential "diacetylene zipper" and Sonogashira coupling reactions

Abstract A reaction sequence consisting of the “Diacetylene zipper” of buta-1,3-diynes from internal to terminal isomers, followed by Sonogashira cross-coupling with 3-,4- or 5-iodopyrazoles, was investigated as a new approach to buta-1,3-diynyl- N -methylpyrazoles. Various pyrazoles bearing alkyl and hydroxyalkyl containing buta-1,3-diyne substituents in the 3-,4- or 5-position and functional groups at the neighboring positions of the ring were obtained.