Banca de DEFESA: YURI ANTONIO FORTUNATO DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : YURI ANTONIO FORTUNATO DA SILVA
DATE: 17/06/2025
TIME: 14:30
LOCAL: on line
TITLE:

 

Computational Study of the Formation of O-Glycosides- 2,3-Unsaturated via Ferrier Rearrangement

KEY WORDS:

Computational study. Ferrier rearrangement. O-glycosides-2,3-unsaturated.

PAGES: 47
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Química Teórica
SUMMARY:

We studied the formation of new 2,3-unsaturated O-glycosides via Ferrier rearrangement using electronic structure calculations at the B3LYP/6-31g+, B3LYP/LAN2DZ, PBEPBE/6-311g, Hartree-Fock/6-311g and AM1 levels. We analyzed some factors that may induce the majority formation of the α-anomer by Ferrier rearrangement, such as the contribution of hyperconjugation, repulsion of the acetoxy group with the nucleophile and the formation of ankimeric assistance intermediates. Based on the total electronic energy and the Gibbs free energy, it was possible to indicate the formation of an intermediate stabilized by anochemical assistance at C3, which explains the preferential formation of the α-glucoside. The results show a higher binding energy between the nucleophile and the acetoxy group at C6 in the upper region for the formation of the β-glucoside, which corroborates and justifies the argument for the formation of the ankimeric assistance intermediate at C3 on the upper side, contradicting the hypothesis that the nucleophile is repelled by the acetoxy group. Analyzing the charges before and after the formation of the 2,3- unsaturated O-glycosides shows that the hyperconjugation model of the anomeric effect is not a decisive factor for the preferential formation of the α-anomer. Finally, of all the factors, the most plausible factor favoring the preferential formation of the α anomer is the spontaneous formation of the intermediate at C3, which prevents the formation of the β anomer.

COMMITTEE MEMBERS:
Presidente - CRISTIANO COSTA BASTOS
Interno - EDUARDO DE CASTRO AGUIAR
Externa ao Programa - 1552304 - SARA CRISTINA PINTO RODRIGUES - UFRPE