A DFT study of [3+2] cycloaddition reactions of an azomethine imine with N-vinyl pyrrole and N-vinyl tetrahydroindole.
The mechanism and selectivities of the [3+2] cycloaddition (32CA) reactions of azomethine imine (AI) 8 with two N-vinyl five-membered heterocycles (NVFH), 9a and 9b, have been theoretically studied using DFT methods at the MPWB1K/6-31G(d) computational level. The possible ortho/meta regio- and endo/exo stereoselective channels were explored and characterised. The low polar character of these 32CA reactions, which is the consequence of the high nucleophilic character of both reagents, as well as the non-effective reactivity of these NVFH as nucleophiles, accounts for the high calculated activation energies, 16.1 (9a) and 16.8 (9b) kcalmol-1in chlorobenzene. Analysis of the relative electronic and free energies associated with the different reaction pathways indicates that the 32CA reactions of the AI with these NVFH are highly meta regioselective but present a poor stereoselectivity, in agreement with the experimental observations. Finally, electron localisation function (ELF) topological analysis allows characterising the mechanism of these 32CA reactions as a non-concerted two-stage one-step mechanism.
Department of Organic Chemistry, University of Valencia, Dr. Moliner 50, E-46100, Burjassot, Valencia, Spain. Electronic address: m.mar.rios@uv.es.
Mar
M
Ríos-Gutiérrez
Laboratoire de Synthèse et Biocatalyse Organique, Département de Chimie, Faculté des Sciences, Université Badji Mokhtar Annaba, BP 12, 23000 Annaba, Algeria.
Fouad
F
Chafaa
Laboratoire de Synthèse et Biocatalyse Organique, Département de Chimie, Faculté des Sciences, Université Badji Mokhtar Annaba, BP 12, 23000 Annaba, Algeria; Département de Physique et Chimie, Ecole Normale Supérieure d'Enseignement Technologique de Skikda, Azzaba, Skikda, Algeria. Electronic address: khorief.abdelmalek@univ-annaba.org.
Abdelmalek
A
Khorief Nacereddine
Laboratoire de Synthèse et Biocatalyse Organique, Département de Chimie, Faculté des Sciences, Université Badji Mokhtar Annaba, BP 12, 23000 Annaba, Algeria.
Abdelhafid
A
Djerourou
Department of Organic Chemistry, University of Valencia, Dr. Moliner 50, E-46100, Burjassot, Valencia, Spain.
Luis R
LR
Domingo
D001391:Azo Compounds / Q000737:chemistry*; D061565:Cycloaddition Reaction; D004583:Electrons; D019277:Entropy; D007097:Imines / Q000737:chemistry*; D007202:Indicators and Reagents; D007211:Indoles / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D011758:Pyrroles / Q000737:chemistry*; D011789:Quantum Theory; D013237:Stereoisomerism; D013882:Thiosemicarbazones / Q000737:chemistry*; D014753:Vinyl Compounds / Q000737:chemistry
D001391:Azo Compounds; D007097:Imines; D007202:Indicators and Reagents; D007211:Indoles; D011758:Pyrroles; D013882:Thiosemicarbazones; D014753:Vinyl Compounds; C512188:azomethine
Azomethine imines; DFT calculations; Molecular mechanism; Selectivity; Vinyl pyrroles; [3+2] Cycloadditions