- Kinetics and mechanism of the formation of mono- and di-phthalate esters catalysed by titanium and tin alkoxides
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The kinetics and mechanism of the formation of phthalate mono-esters and phthalate di-esters from phthalic anhydride and a variety of mono- and di-hydric alcohols are reported and discussed. The kinetic work is extended to a mechanistic study of the same reactions using titanium tetra-n-butoxide and tri-n-butyltin ethoxide as catalysts. The results support a mechanism involving alkoxy ligand exchange at the metal as a crucial step in the catalysis.
- Hinde, Nicholas J.,Hall, C. Dennis
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- Design and synthesis of tricyclic terpenoid derivatives as novel PTP1B inhibitors with improved pharmacological property and in vivo antihyperglycaemic efficacy
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Overexpression of protein tyrosine phosphatase 1B (PTP1B) induces insulin resistance in various basic and clinical research. In our previous work, a synthetic oleanolic acid (OA) derivative C10a with PTP1B inhibitory activity has been reported. However, C10a has some pharmacological defects and cytotoxicity. Herein, a structure-based drug design approach was used based on the structure of C10a to elaborate the smaller tricyclic core. A series of tricyclic derivatives were synthesised and the compounds 15, 28 and 34 exhibited the most PTP1B enzymatic inhibitory potency. In the insulin-resistant human hepatoma HepG2 cells, compound 25 with the moderate PTP1B inhibition and preferable pharmaceutical properties can significantly increase insulin-stimulated glucose uptake and showed the insulin resistance ameliorating effect. Moreover, 25 showed the improved in vivo antihyperglycaemic potential in the nicotinamide–streptozotocin-induced T2D. Our study demonstrated that these tricyclic derivatives with improved molecular architectures and antihyperglycaemic activity could be developed in the treatment of T2D.
- Chen, Feng,Chen, Jiabao,Gao, Cheng,Li, Junyan,Liu, Siyan,Qian, Shan,Wang, Zhouyu,Yang, Lingling,Zhang, Yuanyuan
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p. 152 - 164
(2019/11/25)
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- Preparation of unsaturated polyesters using boric acid as mild catalyst and their sulfonated derivatives as new family of degradable polymer surfactants
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Boric acid-pyridine mixture is presented as mild catalyst for polycondensation of semi-esters of ethylene glycol, in situ-generated by " cyclic anhydride-diol" reaction scheme from maleic, succinic and phthalic anhydrides. This catalyst system was demonstrated to give colorless polyesters in low molecular weights (Mn: 1650-1950 Da) within 4 h at 130 °C 1H NMR spectra of the polyesters derived from maleic anhydride revealed significant isomerization of maleate groups to fumarate units (~80 %) during the polyesterification. Maleate and fumarate double bonds of the unsaturated polyesters (USP) were demonstrated to add bisulfite ions quantitatively to give sulfonated polyesters. The resulting sulfonated polyesters with 50% and 70% succinate units exhibited relatively narrow size spherical and ellipsoidal micelles in aqueous solutions, as inferred from surface tension, DLS and ESEM measurements. The results showed that, this procedure allows preparing a new family of polymer surfactants with tunable hydrophilicity and degradable polyester backbones.
- Alemdar, Neslihan,Erciyes, A. Tuncer,Bicak, Niyazi
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experimental part
p. 5044 - 5050
(2011/11/14)
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- Ninhydrin as a source of naphthoquinone acetals and benzocycloheptenetrione derivatives, and the trapping of an oxacarbene derived from a cyclopentanone
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1,3-Bis(ethylenedioxy)-2-indanone (2) was shown to react with some dienophiles to give naphthoquinone acetals under photochemical reaction conditions, presumably by photodecarbonylation via the corresponding ortho-quinodimethane. With maleic anhydride the highly oxygenated benzocycloheptane derivative rac-12 was obtained in good yield. In a similar manner, upon irradiation in the presence of acrylonitrile a 2:1 mixture of ring-expanded regioisomers rac-13 and rac-14 was obtained. Irradiation in the presence of fumarodinitrile unexpectedly gave the spirocyclic compound rac-15, which was characterized by X-ray crystallography, rac-15 is the trapping product of oxacarbene 16, thus demonstrating a rare case of a ring expansion of a cyclopentanone to give a six-membered ring oxacarbene, here leading to an orthoester. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
- Leinweber, Dirk,Schnebel, Matthias,Wartchow, Rudolf,Wey, Hans G.,Butenschoen, Holger
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p. 2385 - 2390
(2007/10/03)
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