title: Synthesis of diversely 1,3,5-trisubstituted pyrazoles via 5-exo-dig cyclization.
abstract: 5-Exo-dig cyclocondensation of alk-3-yn-1-ones with hydrazines, in the presence of montmorillonite K-10, provides an effective method with a high atom economy for the synthesis of diversely 1,3,5-trisubstituted pyrazoles. The microwave-accelerated reaction proceeds in the absence of solvent and leads to 5-benzyl substituted pyrazoles with good yields (72-91%). The regiochemistry of the process was confirmed by the X-ray crystallographic structure determination of 1-(2-fluorophenyl)-5-(4-methylbenzyl)-3-phenyl-1H-pyrazole.
authors.affiliation: Department of Chemistry, University of Massachusetts Boston, 100 Morrissey Blvd., Boston, MA 02125, USA.
authors.forename: Dmitry A
authors.initials: DA
authors.lastname: Borkin
authors.forename: Mirela
authors.initials: M
authors.lastname: Puscau
authors.forename: Alena
authors.initials: A
authors.lastname: Carlson
authors.forename: Agnes
authors.initials: A
authors.lastname: Solan
authors.forename: Kraig A
authors.initials: KA
authors.lastname: Wheeler
authors.forename: Béla
authors.initials: B
authors.lastname: Török
authors.forename: Roman
authors.initials: R
authors.lastname: Dembinski
mesh_terms: D003500:Cyclization; D006834:Hydrazines / Q000737:chemistry; D015394:Molecular Structure; D011720:Pyrazoles / Q000138:chemical synthesis*
chemical_list: D006834:Hydrazines; D011720:Pyrazoles