119066-29-4Relevant academic research and scientific papers
Reaction monitoring using online vs tube NMR spectroscopy: Seriously different results
Foley, David A.,Dunn, Anna L.,Zell, Mark T.
, p. 451 - 456 (2016)
We report findings from the qualitative evaluation of nuclear magnetic resonance (NMR) reaction monitoring techniques of how each relates to the kinetic profile of a reaction process. The study highlights key reaction rate differences observed between the various NMR reaction monitoring methods investigated: online NMR, static NMR tubes, and periodic inversion of NMR tubes. The analysis of three reaction processes reveals that rates derived from NMR analysis are highly dependent on monitoring method. These findings indicate that users must be aware of the effect of their monitoring method upon the kinetic rate data derived from NMR analysis.
NMR investigations on the proline-catalyzed aldehyde self-condensation: Mannich mechanism, dienamine detection, and erosion of the aldol addition selectivity
Schmid, Markus B.,Zeitler, Kirsten,Gschwind, Ruth M.
body text, p. 3005 - 3015 (2011/06/28)
The proline-catalyzed self-condensation of aliphatic aldehydes in DMSO with varying amounts of catalyst was studied by in situ NMR spectroscopy. The reaction profiles and intermediates observed as well as deuteration studies reveal that the proline-catalyzed aldol addition and condensation are competing, but not consecutive, reaction pathways. In addition, the rate-determining step of the condensation is suggested to be the C-C bond formation. Our findings indicate the involvement of two catalyst molecules in the C-C bond formation of the aldol condensation, presumably by the activation of both the aldol acceptor and donor in a Mannich-type pathway. This mechanism is shown to be operative also in the oligomerization of acetaldehyde with high proline amounts, for which the first in situ detection of a proline-derived dienamine was accomplished. In addition, the diastereoselectivity of the aldol addition is evidenced to be time-dependent since it is undermined by the retro-aldolization and the competing irreversible aldol condensation; here NMR reaction profiles can be used as a tool for reaction optimization.
Consecutive proline-catalyzed aldol reactions and metal-mediated allylations: Rapid entries to polypropionates
K?llstr?m, Sara,Erkkil?, Anniina,Pihko, Petri M.,Sj?holm, Rainer,Sillanp??, Reijo,Leino, Reko
, p. 751 - 756 (2007/10/03)
A concise method for the rapid construction of polypropionate-type structures by consecutive organocatalytic aldol and metal-mediated allylation reactions is described.
