The recently developed artificial force induced reaction (AFIR) method was applied to search systematically all possible multicomponent pathways for the Biginelli reaction mechanism. The most favorable pathway starts with the condensation of the urea and benzaldehyde, followed by the addition of ethyl acetoacetate. Remarkably, a second urea molecule catalyzes nearly every step of the reaction. Thus, the Biginelli reaction is a urea-catalyzed multicomponent reaction. The reaction mechanism was found to be identical in both protic and aprotic solvents.
Phosphorylation of
alcohols is a fundamentally important reaction
in both life science and physical science. Product phosphate monoesters
play key roles in living organisms, natural products, pharmaceuticals,
and organic materials. Most of the chemical methods to date for synthesizing
phosphate monoesters, however, require multistep sequences or are
limited to specific types of substrates possibly due to harsh conditions.
An alternative way to enable the simple production of phosphate monoesters
from highly functionalized precursor alcohols is, thus, highly desired.
We report herein a catalytic phosphorylation of alcohols with high
functional group tolerance using tetrabutylammonium hydrogen sulfate
(TBAHS) and phosphoenolpyruvic acid monopotassium salt (PEP-K) as
the catalyst and phosphoryl donor, respectively. This method enables
the direct introduction of a nonprotected phosphate group to the hydroxy
group of a diverse menu of alcohol substrates, including functionalized
small molecules, carbohydrates, and unprotected peptides. Nuclear
magnetic resonance, mass spectrometric, and density functional theory
analyses suggest that an unprecedented mixed anhydride species, generated
from PEP-K and TBAHS, acts as an active phosphoryl donor in this reaction.
This operationally simple and chemoselective catalytic phosphorylation
allows for the efficient production of densely functionalized O-phosphorylated compounds, which are useful in diverse
fields including biology and medicine.
Isomerization and transformation of glucose and fructose to 5-hydroxymethylfurfural (HMF) in both ionic liquids (ILs) and water has been studied by the reference interaction site model self-consistent field spatial electron density distribution (RISM-SCF-SEDD) method coupled with ab initio electronic structure theory, namely coupled cluster single, double, and perturbative triple excitation (CCSD(T)). Glucose isomerization to fructose has been investigated via cyclic and open chain mechanisms. In water, the calculations support the cyclic mechanism of glucose isomerization; with the predicted activation free energy is 23.8 kcal mol(-1) at experimental condition. Conversely, open ring mechanism is more favorable in ILs with the energy barrier is 32.4 kcal mol(-1) . Moreover, the transformation of fructose into HMF via cyclic mechanism is reasonable; the calculated activation barriers are 16.0 and 21.5 kcal mol(-1) in aqueous and ILs solutions, respectively. The solvent effects of ILs could be explained by the decomposition of free energies and radial distribution functions of solute-solvent that are produced by RISM-SCF-SEDD.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.