Science Faculty

Control of the Dual Reactivity (Iminium-Dienamine) of beta-Arylmethyl alpha,beta-Unsaturated Aldehydes in Organocatalytic 1,3-Dipolar Cycloadditions with N-Benzoyl C,N-Cyclic Azomethine Imines

Author/s

Izquierdo, C.; Esteban, F.; Parra, A.; Alfaro, R.; Alemán, J.; Fraile, A.; García Ruano, J. L.

Año de edición

2014

Referencia completa

J. Org. Chem. 2014, 79, 10417−10433. DOI: 10.1021/jo5018519

Resumen

1,3-Dipolar cycloadditions of C,N-cyclic azomethineimines 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 iminiumdienamine 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.