Brønsted acid catalyzed morita-baylis-hillman reaction: A new mechanistic view for thioureas revealed by ESI-MS(/MS) monitoring and DFT calculations

Giovanni W. Amarante, Mario Benassi, Humberto M.S. Milagre, Ataualpa A.C. Braga, Feliu Maseras, Marcos N. Eberlin, Fernando Coelho

Research output: Contribution to journalArticleResearchpeer-review

70 Citations (Scopus)

Abstract

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 transitionstate (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 Brønsted acid stabilizing the basic oxygen center that is formed in the TS. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.
Original languageEnglish
Pages (from-to)12460-12469
JournalChemistry - A European Journal
Volume15
Issue number45
DOIs
Publication statusPublished - 1 Jan 2009

Keywords

  • Density functional calculations
  • ESI mass spectrometry
  • Morita-baylis-hiliman reaction
  • Reaction mechanisms
  • Thiourea

Fingerprint Dive into the research topics of 'Brønsted acid catalyzed morita-baylis-hillman reaction: A new mechanistic view for thioureas revealed by ESI-MS(/MS) monitoring and DFT calculations'. Together they form a unique fingerprint.

Cite this