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- Title
Diradical-singlet character of 1,3-dipoles affects reactivity of 1,3-dipolar cycloaddition reactions and intramolecular cyclization.
- Authors
Fiorot, Rodolfo G.; Vilhena, Felipe de S.; Carneiro, José W. de M.
- Abstract
1,3-Dipolar cycloaddition (1,3-DC) reactions are powerful synthetic tool to obtain highly functionalized 5-membered heterocycles, starting from a 1,3-dipole and a dipolarophile in a single step. The reactivity of these systems is usually rationalized in terms of Frontier Molecular Orbital Theory (FMOT), which neglects a possible contribution of an open-shell weakly coupled singlet-diradical specie. In this work, the broken-symmetry approach is used to estimate the singlet-diradical character of 18 dipoles of the second period of the periodic table, classified as allyl-type N-centered, allyl-type O-centered, and propargyl-type 1,3-dipoles, providing a rationalization for 1,3-DC reactivity. The intramolecular cyclization of bent allyl-type N- and O-centered dipoles into 3-membered rings was also analyzed, and revealed that the energetic change is associated with the spin densities of peripheral atoms. Finally, a close relationship between the energy for the ring-opening process of the cyclic configuration and the reactivity of 1,3-dipoles toward 1,3-dipolar cycloaddition reaction was also found.
- Subjects
RING formation (Chemistry); FRONTIER orbitals; PYRROLIDINE synthesis; RING-opening reactions
- Publication
Journal of Molecular Modeling, 2019, Vol 25, Issue 10, p1
- ISSN
1610-2940
- Publication type
Article
- DOI
10.1007/s00894-019-4162-9