Regio- and stereochemistry of [2 + 2] photocycloadditions of imines to alkenes: a computational and experimental study.
The [2 + 2] photocycloaddition of isoxazolines to alkenes has been studied by means of CASPT2/6-31G*//CASSCF/6-31G*. The reaction outcome is influenced by the relative ratio of imine deactivation and photocycloaddition. Analysis of the conical intersection points involved in the photoreaction shows that fast deactivation is prevented when an electron-withdrawing group is placed in any position that can affect the imine moiety. Computational data predict that the photoreaction will be regiospecific but without stereoselectivity. Furthermore, the favored regioisomer will be different for alkenes with electron-withdrawing or electron-releasing substituents. The results of a complementary experimental study correlate well with the computational data. Several conclusions included in the present work could prove useful for the generalization of the photocycloaddition of imines.
Sampedro
Diego
D
Departamento de Química, Universidad de La Rioja, Grupo de Síntesis Química de La Rioja, Unidad Asociada al C.S.I.C., Madre de Dios, 51, 26006 Logroño, Spain. diego.sampedro@unirioja.es
Soldevilla
Alberto
A
Campos
Pedro J
PJ
Ruiz
Roberto
R
Rodríguez
Miguel A
MA