Evaluation of the Katsuki-Sharpless Epoxidation Precatalysts by ESI-FTMS, CID, and IRMPD Spectroscopy

Autor(es)

Fernandes, Andre Santos ^[1] ; Maitre, Philippe ^[2] ; Correra, Thiago Carita ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Chem, Dept Fundamental Chem, Av Prof Lineu Prestes 748, BR-05508000 Sao Paulo, SP - Brazil

^[2] Univ Paris Saclay, Univ Paris Sud, CNRS, URM8000, Lab Chim Phys, F-91405 Orsay - France

• Tipo de documento: Artigo Científico
• Fonte: Journal of Physical Chemistry A; v. 123, n. 5, p. 1022-1029, FEB 7 2019.
• Citações Web of Science: 1

Resumo

The Katsuki-Sharpless epoxidation reaction is one of the most recognized chiral catalytic reactions, allowing for chiral epoxides to be used as starting materials for a series of synthetic pathways. The complete understanding of this reaction mechanism depends on the identification and description of species formed from Ti(IV) alkoxides and alkyl tartrates precatalysts. Despite previous reports on the nature of a bimetallic catalyst based on IR spectroscopy and NMR analysis, some debate remains. Therefore, we carried out mass spectrometry analysis by direct extraction of the ions from the reaction media by ESI(-)-FT-ICR and evaluated the observed ions by CID and IRMPD experiments. These techniques allowed us to detect carboxylates that correlate to the species in the reaction media and to confirm the actual presence of the titanium-tartrate complexes in solution. Our IRMPD results suggest the carboxylate dimer as an asymmetric species with two tartrates coordinated to a single Ti atom, while the other Ti center is coordinated by labile alkoxydes that could be easily exchanged by the organic peroxide and the substrate, allowing the epoxidation reaction to take place. (AU)

• Processo FAPESP: 15/11769-9 - Isolamento de intermediários reativos da epoxidação de Sharpless e caracterização dessas espécies por cálculos teóricos
• Beneficiário: André Santos Fernandes
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica
• Processo FAPESP: 14/15962-5 - Mecanismos de reação de sistemas catalíticos assimétricos por espectrometria de massas e espectroscopia vibracional de íons na fase gasosa
• Beneficiário: Thiago Carita Correra
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 15/08539-1 - EMU concedido no processo 2014/15962-5: espectrômetro de massas tipo íon TRAP modificado para realização de espectroscopia vibracional no infravermelho (IRMPD)
• Beneficiário: Thiago Carita Correra
• Modalidade de apoio: Auxílio à Pesquisa - Programa Equipamentos Multiusuários