title: Cascade cyclization, dipolar cycloaddition of azomethine imines for the synthesis of pyrazolidines.
abstract: A tandem multi-step, one-pot reaction of aldehydes with hydrazines has been used for the preparation of tetrahydropyrazoles and dihydropyrazoles. The chemistry involves condensation then cyclization, followed by inter- or intramolecular dipolar cycloaddition of the resulting azomethine imine intermediates. The intramolecular cycloaddition gives fused tricyclic compounds as single diastereoisomers. The intermolecular cycloaddition was successful with a variety of activated alkene and alkyne dipolarophiles.
authors.affiliation: Department of Chemistry, University of Sheffield, Brook Hill, Sheffield, UK S3 7HF.
authors.forename: Hélène D S
authors.initials: HD
authors.lastname: Guerrand
authors.forename: Harry
authors.initials: H
authors.lastname: Adams
authors.forename: Iain
authors.initials: I
authors.lastname: Coldham