title: Gold-catalyzed three-component spirocyclization: a one-pot approach to functionalized pyrazolidines.
abstract: An efficient, highly atom economic synthesis of hitherto unknown spirocyclic pyrazolidines in a one-pot process was developed. The gold-catalyzed three-component coupling of alkynols, hydrazines and aldehydes or ketones likely proceeds via cycloisomerization of the alkynol to an exocyclic enol ether and subsequent [3 + 2]-cycloaddition of an azomethine ylide. A library of 29 derivatives with a wide range of functional groups was synthesized in up to 97% yield. With this new method, every position in the final product can be substituted which renders the method ideal for applications in combinatorial or medicinal chemistry.
authors.affiliation: Organic Chemistry, Dortmund University of Technology, Otto-Hahn-Str. 6, D-44227 Dortmund, Germany. norbert.krause@tu-dortmund.de.
authors.forename: Bernd
authors.initials: B
authors.lastname: Wagner
authors.affiliation: Organic Chemistry, Dortmund University of Technology, Otto-Hahn-Str. 6, D-44227 Dortmund, Germany. norbert.krause@tu-dortmund.de.
authors.forename: Wolf
authors.initials: W
authors.lastname: Hiller
authors.affiliation: Kyoto University, Graduate School of Pharmaceutical Sciences, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ohno
authors.affiliation: Organic Chemistry, Dortmund University of Technology, Otto-Hahn-Str. 6, D-44227 Dortmund, Germany. norbert.krause@tu-dortmund.de.
authors.forename: Norbert
authors.initials: N
authors.lastname: Krause
mesh_terms: D002384:Catalysis; D003500:Cyclization; D006046:Gold / Q000737:chemistry*; D015394:Molecular Structure; D011720:Pyrazoles / Q000138:chemical synthesis* / Q000737:chemistry; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D011720:Pyrazoles; D013141:Spiro Compounds; D006046:Gold