- Hydrogen-Bonding Catalyzed Ring-Closing C?O/C?O Metathesis of Aliphatic Ethers over Ionic Liquid under Metal-Free Conditions
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O-heterocycles have wide applications, and their efficient and green synthesis is very interesting. Herein, we report hydrogen-bonding catalyzed ring-closing metathesis of aliphatic ethers to O-heterocycles over ionic liquid (IL) catalyst under metal- and solvent-free conditions. The IL 1-butylsulfonate-3-methylimidazolium trifluoromethanesulfonate ([SO3H-BMIm][OTf]) is discovered to show outstanding performance, better than the reported catalysts. An interface effect plays an important role in mediating the reaction rate due to the immiscibility between the products and the IL catalyst, and the products can be spontaneously separated. NMR analysis and DFT calculation suggest that a pair of cation and anion of [SO3H-BMIm][OTf] could form three strong H-bonds with an ether molecule, which catalyze the ether transformation via a cyclic oxonium intermediate. A series of O-heterocycles including tetrahydrofurans, tetrahydropyrans, morpholines and dioxane can be obtained from their corresponding ethers in excellent yields (e.g., >99 %). This work opens an efficient and metal-free way to produce O-heterocycles from aliphatic ethers.
- Wang, Huan,Zhao, Yanfei,Zhang, Fengtao,Wu, Yunyan,Li, Ruipeng,Xiang, Junfeng,Wang, Zhenpeng,Han, Buxing,Liu, Zhimin
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supporting information
p. 11850 - 11855
(2020/05/16)
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- 2,6-dione-piperazine (piperidine) derivative and its application
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The invention discloses a 2,6-diketone-piperazine (piperidine) type derivative and an application thereof. The derivative can be applied to preparation of medicines for preventing or treating central nervous system diseases. Animal experiment results show that the derivative has smaller ED50 and stronger action in MK-801-induced high activity and apomorphine-induced climbing animal models as well as has larger ED50 and larger therapeutic indexes in an animal catalepsy model. The derivative is a compound or salt thereof with a general formula (I).
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Paragraph 0061; 0068
(2016/10/07)
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- Solid-phase synthesis of a nonpeptide RGD mimetic library: New selective αvβ3 integrin antagonists
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The solid-phase synthesis of a low molecular weight RGD mimetic library is described. Activities of the compounds in inhibiting the interaction of ligands, vitronectin and fibrinogen, with isolated immobilized integrins αvβ3 and αIIbβ3 were determined in a screening assay. Highly active and selective nonpeptide αvβ3 integrin antagonists with regard to orally bioavailability were developed, based on the aza-glycine containing lead compound 1. An important variation is the substitution of the aspartic amide of 1 by an aromatic residue. Furthermore, different guanidine mimetics have been incorporated to improve the pharmacokinetic profile. Exchange of the β-amino acid NH by a methylene moiety in one set of RGD mimetics leads to the azacarba analogue compounds representing a novel peptidomimetic approach, which should increase the metabolic stability.
- Sulyok,Gibson,Goodman,H?lzemann,Wiesner,Kessler
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p. 1938 - 1950
(2007/10/03)
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