title: Syntheses of Tetrahydropyridazine and Tetrahydro-1,2-diazepine Scaffolds through Cycloaddition Reactions of Azoalkenes with Enol Diazoacetates.
abstract: Catalyst-dependent [4 + 2]-cycloaddition reactions of azoalkenes from α-halohydrazones with enol diazoacetates have been developed. A [4 + 2]-cycloaddition of enol diazoacetates with in situ formed azoalkenes produces tetrahydropyridazinyl-substituted diazoacetates promoted by only Cs2CO3. In contrast, donor-acceptor cyclopropenes, which are formed in situ from enol diazoacetates by Rh2(OAc)4-catalyzed dinitrogen extrusion, undergo [4 + 2]-cycloaddition with azoalkenes to yield bicyclo[4.1.0]tetrahydropyridazines. These stable cycloaddition products undergo subsequent one-step transformations to form 6-alkylidenetetrahydropyridazines and 4,5,6,7-tetrahydro-1,2-diazepine derivatives in good yields.
authors.affiliation: Department of Chemistry, The University of Texas at San Antonio , San Antonio, Texas 78249, United States.
authors.forename: Yongming
authors.initials: Y
authors.lastname: Deng
authors.affiliation: College of Chemistry, Chemical Engineering and Materials Science, Soochow University , Suzhou 215123, P. R. China.
authors.forename: Chao
authors.initials: C
authors.lastname: Pei
authors.affiliation: Department of Chemistry, The University of Texas at San Antonio , San Antonio, Texas 78249, United States.
authors.forename: Hadi
authors.initials: H
authors.lastname: Arman
authors.affiliation: College of Chemistry, Chemical Engineering and Materials Science, Soochow University , Suzhou 215123, P. R. China.
authors.forename: Kuiyong
authors.initials: K
authors.lastname: Dong
authors.affiliation: College of Chemistry, Chemical Engineering and Materials Science, Soochow University , Suzhou 215123, P. R. China.
authors.forename: Xinfang
authors.initials: X
authors.lastname: Xu
authors.affiliation: Department of Chemistry, The University of Texas at San Antonio , San Antonio, Texas 78249, United States.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Doyle