title: Synthesis of Novel Pyrazoles via [2+3]-Dipolar Cycloaddition Using Alkyne Surrogates.
abstract: The syntheses of an important class of hitherto unreported novel pyrazoles are described. The regioselective synthesis of 1,3,4,5-tetrasubstituted pyrazoles was achieved by the Huisgen cyclization of nitrile imines with a trisubstituted bromoalkene. The substituted bromoalkene functions as an alkyne synthon which was used to construct 5,5-disubstituted bromopyrazoline intermediates that undergo aromatization to the analogous pyrazoles through the loss of HBr. The cycloaddition regioselectivity was confirmed through single X-ray crystal data of one of the pyrazoles.
authors.affiliation: Department of Chemistry & Biochemistry, College of Science, Engineering and Technology, Jackson State University, Jackson, Mississippi 39217 USA.
authors.forename: Sureshbabu
authors.initials: S
authors.lastname: Dadiboyena
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Valente
authors.forename: Ashton T
authors.initials: AT
authors.lastname: Hamme