title: Total Facial Discrimination of 1,3-Dipolar Cycloadditions in a d-Erythrose 1,3-Dioxane Template: Computational Studies of a Concerted Mechanism.
abstract: A new d-erythrose 1,3-dioxane derivative was synthesized from d-glucose and found to be a highly stereoselective template as a dipolarophile. Different 1,3-dipoles of allenyl-type were employed, giving different regioselectivities, depending on its nature; the regioselectivity is complete with alkyl azides and phenyldiazomethane, but is inexistence with nitrile oxides. Computational studies were performed to understand the mechanisms of cycloadditions. All the studied cycloadditions were found to be concerted involving small free activation energies and are all exoenergonic. The stereoselectivity is due to a combined result of the steric effect H-8a and the hyperconjugative effect of the *C-O to the incoming 1,3-dipole. The regioselectivity observed in alkyl azides and phenyldiazomethane is mostly dependent on the distortion effect during the cycloaddition process. This distortion effect is however higher in the alkyl azide compounds than in phenyldiazomethane.
authors.affiliation: Departamento de Química, Universidade do Minho , Campus de Gualtar, 4710-057 Braga, Portugal.
authors.forename: Cristina E A
authors.identifier: 0000-0002-4195-712X
authors.initials: CE
authors.lastname: Sousa
authors.affiliation: Departamento de Química, Universidade do Minho , Campus de Gualtar, 4710-057 Braga, Portugal.
authors.forename: António M P
authors.initials: AM
authors.lastname: Ribeiro
authors.affiliation: Departamento de Química, Universidade do Minho , Campus de Gualtar, 4710-057 Braga, Portugal.
authors.forename: António
authors.initials: A
authors.lastname: Gil Fortes
authors.affiliation: REQUIMTE/UCIBIO, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto , Rua do Campo Alegre s/n, 4169-007 Porto, Portugal.
authors.forename: Nuno M F S A
authors.initials: NM
authors.lastname: Cerqueira
authors.affiliation: Departamento de Química, Universidade do Minho , Campus de Gualtar, 4710-057 Braga, Portugal.
authors.forename: Maria J
authors.identifier: 0000-0002-1864-2277
authors.initials: MJ
authors.lastname: Alves