Chiral cyclohexanohemicucurbit[n]urils with multiple interaction sites induce chirality on planar zinc porphyrins and bind up to three porphyrin molecules.
The first tris(O‒I‒N) carbonyl hypoiodites have been synthesised based on trimesic acid and pyridine or 4-methylpyridine, with their structures definitively confirmed by single crystal X-ray diffraction (SCXRD). The more soluble...
An asymmetric Michael addition of malononitrile to vinyl phosphonates was accomplished by hydrogen bond-enhanced bifunctional halogen bond (XB) catalysis.
An asymmetric phase-transfer-catalyzed N-alkylation of substituted indoles with various Michael acceptors was studied. Acidities of nitroindoles were determined in acetonitrile by UV-Vis spectrophotometric titration. There was essentially no correlation between acidity and reactivity in the aza-Michael reaction. The position of the nitro group on the indole ring was essential to control the stereoselectivity of the reaction. Michael adducts were obtained in high yields and moderate enantioselectivities in the reaction between 4-nitroindole and various Michael acceptors in the presence of cinchona alkaloid based phase-transfer catalysts. In addition to outlining the scope and limitations of the method, the geometries of the transition states of the reaction were calculated.
An efficient enantioselective organocatalytic
method for the synthesis
of N-alkylated indoles with α-branched alkyl
substituents from the corresponding unsaturated indolyl ketones via
a Michael addition has been developed. The resulting products were
obtained in high enantioselectivities and in good yields. Various
nucleophiles (nitroalkanes, malononitrile, malonic esters) can be
used. The substitution pattern of the indole ring had no significant
impact on the reaction outcome. Both electron-withdrawing and electron-donating
substituents in any position of the heteroaromatic ring were well-tolerated.
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