The synthesis of both trans- and cis-diastereomers of pyrrolidinine-thioxotetrahydropyrimidinone bearing either a fluorine or a hydroxyl group was accomplished. The new compounds were tested for their catalytic properties in a variety of asymmetric organic transformations and compared with the first generation catalyst. It was found that the new catalysts could efficiently catalyze the reactions in brine, without the use of organic solvent, and by employing an almost stoichiometric amount of reagents. Thus, the products were isolated by simple extractions, avoiding the use of chromatography in excellent yields, diastereoselectivities, and enantioselectivities.
Along the lines of modern sustainable oxidation, a green and mild organocatalytic synthetic procedure for the synthesis of hydroxylactones from alkenoic acids is described. The reaction includes the activation of H2O2 by an organocatalyst (2,2,2‐trifluoromethylacetophenone), the oxidation of an olefinic group to the corresponding epoxide, and intramolecular lactonization to afford a variety of substituted γ‐ or δ‐lactones with multiple substitution patterns in good to high yields. The product can be obtained with high purity after simple extraction if the conversion is quantitative. Attempts to render the process asymmetric met with limited success.
A series of 2,3-disubstituted-5-oxochromeno [2,3-b]pyridine derivatives were synthesized under ultrasound irradiation, and also under conventional methods, from the reaction of 3-cyanochromones with some active methylene compounds in the presence of a stoichiometric base. The structures of the products were unambiguously elucidated by 1D and 2D NMR experiments. Full assignment of all 1 H and 13 C NMR chemical shifts has been achieved. In addition, the lipid peroxidation inhibition of the synthesized chromenopyridine derivatives was evaluated.
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