206181-87-5Relevant academic research and scientific papers
Supramolecular Catalysis of Acyl Transfer within Zinc Porphyrin-Based Metal-Organic Cages
Li, Lili,Yang, Linlin,Li, Xuezhao,Wang, Jing,Liu, Xin,He, Cheng
, p. 8802 - 8810 (2021/06/28)
To illustrate the supramolecular catalysis process in molecular containers, two porphyrinatozinc(II)-faced cubic cages with different sizes were synthesized and used to catalyze acyl-transfer reactions between N-acetylimidazole (NAI) and various pyridylcarbinol (PC) regioisomers (2-PC, 3-PC, and 4-PC). A systemic investigation of the supramolecular catalysis occurring within these two hosts was performed, in combination with a host-guest binding study and density functional theory calculations. Compared to the reaction in a bulk solvent, the results that the reaction of 2-PC was found to be highly efficient with high rate enhancements (kcat/kuncat = 283 for Zn-1 and 442 for Zn-2), as well as the different efficiencies of the reactions with various ortho-substituted 2-PC substrates and NAI derivates should be attributed to the cages having preconcentrated and preoriented substrates. The same cage displayed different catalytic activities toward different PC regioisomers, which should be mainly attributed to different binding affinities between the respective reactant and product with the cages. Furthermore, control experiments were carried out to learn the effect of varying reactant concentrations and product inhibition. The results all suggested that, besides the confinement effect caused by the inner microenvironment, substrate transfer, including the encapsulation of the reactant and the release of products, should be considered to be a quite important factor in supramolecular catalysis within a molecular container.
Piperazine and piperidine compounds
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, (2008/06/13)
A group of new piperazine and piperidine compounds having interesting advantageous pharmacological properties and have the formula (a) wherein A represents a heterocyclic group having 5-7 ring atoms wherein 1-3 heteroatoms selected from the group O, N and
Synthesis, rotamer orientation, and calcium channel modulation activities of alkyl and 2-phenethyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(3- or 6-substituted-2-pyridyl)-5-pyridinecarboxylates
Iqbal, Nadeem,Akula, Murthy R.,Vo, Dean,Matowe, Wandikayi C.,McEwen, Carol-Anne,Wolowyk, Michael W.,Knaus, Edward E.
, p. 1827 - 1837 (2007/10/03)
A group of racemic alkyl and 2-phenethyl 1,4-dihydro-2,6-dimethyl-3- nitro-4-(3- or 6-substituted-2-pyridyl)-5-pyridinecarboxylates (13a-q) was prepared using a modified Hantzsch reaction that involved the condensation of a 3- or 6-substituted-2-pyridinecarboxaldehyde (7a-j) with an alkyl or 2- phenethyl 3-aminocrotonate (11a-d) and nitroacetone (12). Nuclear Overhauser (NOE) studies indicated there is a significant rotamer fraction in solution where the pyridyl nitrogen is oriented above the 1,4-dihydropyridine ring, irrespective of whether a substituent is located at the 3- or 6-position. A potential H-bonding interaction between the pyridyl nitrogen free electron pair and the suitably positioned 1,4-dihydropyridine NH moiety may stablize this rotamer orientation. In vitro calcium channel antagonist and agonist activities were determined using guinea pig ileum longitudinal smooth muscle (GPILSM) and guinea pig left atrium (GPLA) assays, respectively. Compounds having an i-Pr ester substituent acted as dual cardioselective calcium channel agonists (GPLA)/smooth muscle-selective calcium channel antagonists (GPILSM), except for the C-4 3-nitro-2-pyridyl compound which exhibited an antagonist effect on both GPLA and GPILSM. In contrast, the compounds with a phenethyl ester group, which exhibited antagonist activity (IC50 = 10-5- 10-7 M range) on GPILSM, were devoid of cardiac agonist activity on GPLA. Structure-activity relationships showing the effect of a substituent (Me, CF3, C1, NO2, Ph) at the 3- or 6-position of a C-4 2-pyridyl moiety and a variety of ester substituents (Me, Et, i-Pr, PhCH2CH2-) upon calcium channel modulation are described. Compounds possessing a 3- or 6-substituted- 2-pyridyl moiety, in conjuction with an i-Pr ester substituent, are novel 1,4-dihydropyridine calcium channel modulators that offer a new drug design approach directed to the treatment of congestive heart failure and may also be useful as probes to study the structure-function relationships of calcium channels.
