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Biotransformations of various functionalized racemic nitriles catalyzed by Rhodococcus erythropolis AJ270, a nitrile hydratase/amidase-containing microbial whole-cell catalyst, were studied. While the nitrile hydratase exhibits high catalytic efficiency but very low enantioselectivity against almost all nitrile substrates examined, the amidase is very… (More)
[reaction: see text] Under acidic conditions, a fluorescence-quenching process of 1 induced by selective binding of alkali metal ions was discovered. The mechanism of this new process involves alkali metal ion-induced deprotonation of the ammonium ion to trigger resumption of a fluorescence-quenching PET process.
[structure: see text] Owing to the electronic nature of the bridging nitrogen atoms which can adopt different hybridizations and form various conjugations with the adjacent pyridine(s), methylazacalixpyridine underwent conformation and cavity preorganization to highly selectively bind the Zn(2+) ion. Rigidification and coplanarity of the macrocyclic ring… (More)
A new approach to the synthesis of meta-substituted enantiopure inherently chiral calixarenes by introducing L-Boc-proline as dual functions of the chiral auxiliary has been described. Moreover, the absolute configurations of the enantiomers were determined by CD spectra, X-ray crystallographic analysis, and the chemical derivative method.
Described herein is a manganese-catalyzed dehydrogenative [4+2] annulation of NH imines and alkynes, a reaction providing highly atom-economical access to diverse isoquinolines. This transformation represents the first example of manganese-catalyzed CH activation of imines; the stoichiometric variant of the cyclomanganation was reported in 1971. The redox… (More)
Methylazacalix[n]pyridines (n = 4, 8) and methylazacalix[m]arene[n]pyridines (m = n = 2, 4) have been synthesized by a convenient fragment coupling approach starting from 2,6-dibromopyridine, 2,6-diaminopyridine, and benzene-1,3-diamine. Thanks to the intrinsic electronic nature of nitrogen, which can adopt mainly sp(2) hybridization, allowing it variously… (More)
Calixaromatics have attracted much attention on molecular recognition owing to their flexible conformations, cavity structures, versatile recognition properties, and functions. However, conformational control of calixaromatics is still a challenging topic in the field of calixaromatics. Therefore, we explore the possibility to control the chirality of… (More)
Large methylazacalix[n]pyridines (n = 6-9) were synthesized effectively from the Pd-catalyzed macrocyclic fragment coupling reactions between alpha,omega-dibrominated and alpha,omega-diaminated linear oligomers. As macrocyclic host molecules, they formed a 1:1 complex with fullerenes C(60) and C(70) with association constants ranging from 3 x 10(4) to 1 x… (More)
A series of inherently chiral calixarenes with cone and partial cone conformations and with crown ether moieties of variable size have been readily synthesized. By taking advantage of the carboxy appendage on the lower rim, these were condensed with the chiral auxiliary (S)-BINOL to form diastereomers which, in most cases, could be separated by… (More)
[structure: see text] The syntheses of five pairs of novel inherently chiral calixarenes are described. Two synthetic routes were adopted to generate racemic 3-carboxylic or 2-carboxylic group substituted calixquinolines in the cone or the partial-cone conformation, respectively. The chiral products were thoroughly characterized by various… (More)