Bronsted Acid Catalyzed Morita-Baylis-Hillman Reaction: A New Mechanistic View for Thioureas Revealed by ESI-MS(/MS) Monitoring and DFT Calculations
Contribuinte(s) |
Universidade Estadual Paulista (UNESP) |
---|---|
Data(s) |
30/09/2013
20/05/2014
30/09/2013
20/05/2014
01/01/2009
|
Resumo |
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) A Morita-Baylis-Hillman (MBH) reaction catalyzed by thiourea was monitored by ESI-MS(/MS) and key intermediates were intercepted and characterized. These intermediates Suggest that thiourea acts as an organocatalyst in all steps of the MBH reaction cycle, including the rate-limiting proton-transfer step. DFT calculations, performed for a model MBH reaction between formaldehyde and acrolein with trimethylamine as base and in the presence or the absence of thiourea, suggest that thiourea accelerates MBH reactions by decreasing the transition-state (TS) energies through bidentate hydrogen bonding throughout the whole catalytic cycle. In the rate-limiting proton-transfer step, the thiourea acts not as a proton shuttle, but as a Bronsted acid stabilizing the basic oxygen center that is formed in the TS. |
Formato |
12460-12469 |
Identificador |
http://dx.doi.org/10.1002/chem.200900966 Chemistry-a European Journal. Weinheim: Wiley-v C H Verlag Gmbh, v. 15, n. 45, p. 12460-12469, 2009. 0947-6539 http://hdl.handle.net/11449/20162 10.1002/chem.200900966 WOS:000272325800034 |
Idioma(s) |
eng |
Publicador |
Wiley-v C H Verlag Gmbh |
Relação |
Chemistry-a European Journal |
Direitos |
closedAccess |
Palavras-Chave | #Density functional calculations #ESI mass spectrometry #Morita-Baylis-Hillman reaction #reaction mechanisms #thiourea |
Tipo |
info:eu-repo/semantics/article |