title: Control of the dual reactivity (iminium-dienamine) of β-arylmethyl α,β-unsaturated aldehydes in organocatalytic 1,3-dipolar cycloadditions with N-benzoyl C,N-cyclic azomethine imines.
abstract: 1,3-Dipolar cycloadditions of C,N-cyclic azomethine imines with α,β-unsaturated aldehydes can be performed with complete control of the regio-, exo-, and enantioselectivity under aminocatalytic conditions. The so far never studied competence of the iminium-dienamine reactivity inherent to β-alkyl α,β-unsaturated aldehydes was studied, which was possible by allowing achievement of complete control of the chemoselectivity in reactions of the β-arylmethyl derivatives with azomethine imines by using different additives and organocatalysts, whose role has been rationalized by DFT calculations and chemical proofs. Thus, it has been possible to selectively obtain the pyrazolidines resulting from both the attack to the C2-C3 (via iminium) and the C3-C4 (via dienamine) bonds at the starting enals, which can be used as precursors of interesting tetrahydroisoquinolinic compounds.
authors.affiliation: Departamento de Química Orgánica (Módulo 1), Facultad de Ciencias, Universidad Autónoma de Madrid , 28049 Madrid, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Izquierdo
authors.forename: Francisco
authors.initials: F
authors.lastname: Esteban
authors.forename: Alejandro
authors.initials: A
authors.lastname: Parra
authors.forename: Ricardo
authors.initials: R
authors.lastname: Alfaro
authors.forename: José
authors.initials: J
authors.lastname: Alemán
authors.forename: Alberto
authors.initials: A
authors.lastname: Fraile
authors.forename: José Luis García
authors.initials: JL
authors.lastname: Ruano
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D001391:Azo Compounds / Q000737:chemistry*; D061565:Cycloaddition Reaction; D007097:Imines / Q000737:chemistry*; D007477:Ions / Q000737:chemistry*; D007546:Isoquinolines / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D013882:Thiosemicarbazones / Q000737:chemistry*
chemical_list: D000447:Aldehydes; D001391:Azo Compounds; D007097:Imines; D007477:Ions; D007546:Isoquinolines; D013882:Thiosemicarbazones; C512188:azomethine