title: A Novel Synthesis of 1,3,5-Trisubstituted Pyrazoles through a Spiro-pyrazoline Intermediate via a Tandem 1,3-Dipolar Cycloaddition/Elimination.
abstract: The syntheses of an important class of hitherto unreported 1,3,5-pyrazoles, inspired by an unanticipated eliminatory ring opening are described. The reported pyrazole compounds were constructed through the Huisgen cyclization of 2-methylene-1,3,3-trimethylindoline and an in situ generated nitrile imine. The newly formed spiro-pyrazoline intermediate presumably then undergoes a ring opening/elimination process to afford a pyrazole, as evidenced by single X-ray crystal data. The current report constitutes the first formal observation of this kind of ring opening involving a spiro-pyrazoline intermediate.
authors.affiliation: Department of Chemistry, 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