2528-16-7Relevant academic research and scientific papers
Proton-exchanged montmorillonite-mediated reactions of methoxybenzyl esters and ethers
Chen, Dongyin,Xu, Chang,Deng, Jie,Jiang, Chunhuan,Wen, Xiaoan,Kong, Lingyi,Zhang, Ji,Sun, Hongbin
, p. 1975 - 1983 (2014/03/21)
Proton-exchanged montmorillonite (H-mont) was found to be an eco-friendly and cost-effective catalyst for the generation of O-methylated quinone methides (QM) from the corresponding p or o-methoxybenzyl esters and ethers. Nucleophilic trapping of the O-methylated QM with arenes, alcohols, 1,3-dicarbonyl compounds, silyl enol ethers, and allylsilanes has been carried out, respectively, leading to eco-friendly benzylation reactions. Using this protocol, H-mont-mediated deprotection of PMB-protected esters and ethers have been realized for the first time. This work would pave the way for further exploration in O-alkylated QM that are of chemical and biological significance.
Suppression of spin-spin coupling in nitroxyl biradicals by supramolecular host-guest interactions
Porel, Mintu,Ottaviani, M. Francesca,Jockusch, Steffen,Jayaraj, Nithyanandhan,Turro, Nicholas J.,Ramamurthy
supporting information; experimental part, p. 7736 - 7738 (2010/11/17)
The use of supramolecular architectures to control the spatially dependent spin exchange (spin communication) between two covalently linked radical centers (biradical) has been explored. Cucurbit[8]uril, through supramolecular steric effect, completely suppresses spin exchange between two adjacent radical centers in a biradical. The Royal Society of Chemistry.
Ring-opening of cyclic anhydrides using ionic liquids
Jiang, Dong,Wang, Yuan Yuan,Xu, Yan Nan,Dai, Li Yi
experimental part, p. 167 - 169 (2009/10/15)
Four novel Bronsted acidic ionic liquids with two different acid sites on the imidazolium cations were synthesised and employed as catalysts and solvents for the ring-opening of cyclic anhydrides to synthesise half-esters. The results showed that these novel Bronsted acidic ionic liquids were efficient and recyclable. Good yields, short reaction times and mild reaction conditions were achieved.
One-step transformation of tetrahydropyranyl ethers using indium(III) triflate as the catalyst
Mineno, Tomoko,Nikaido, Nana,Kansui, Hisao
scheme or table, p. 1167 - 1170 (2010/03/31)
A convergent one-step transformation of tetrahydropyranyl (THP) ethers is described. According to our earlier experiments, indium(III) triflate has proven to be an efficient catalyst for the transformation of THP ethers into their corresponding acetates.
Zwitterionic salts as mild organocatalysts for transesterification
Ishihara, Kazuaki,Niwa, Masatoshi,Kosugi, Yuji
supporting information; experimental part, p. 2187 - 2190 (2009/05/27)
(Chemical Equation Presented) The exothermic reaction of 3,5-bis(trifluoromethyl)phenyl or 4-nitrophenyl isothiocyanate with 4-pyrrolidinopyridine (PPY) gave the corresponding arylaminothiocarbonylpyridinium salts in quantitative yields. These novel zwitterionic salts were effective as organocatalysts for the transesterification reaction of an equimolar mixture of methyl carboxylates and alcohols in hydrocarbons such as heptane and octane under azeotropic reflux conditions with the removal of methanol. In sharp contrast, PPY was inert as a catalyst under the same reaction conditions.
Highly selective deprotection of tert-butyl esters using ytterbium triflate as a catalyst under mild conditions
Sridhar, P. Ramu,Sinha, Surajit,Chandrasekaran
, p. 157 - 160 (2007/10/03)
Ytterbium triflate catalyses the deprotection of tert-butyl esters selectively in the presence of other esters under mild conditions in almost quantitative yields. The reactions are carried out in nitromethane (45°-50°C) using 5 mole percent of the catalyst.
Synthesis and physicochemical assessment of novel 2-substituted 3-hydroxypyridin-4-ones, novel iron chelators
Moridani, Majid Y.,Tilbrook, Gary S.,Khodr, Hicham H.,Hider, Robert C.
, p. 349 - 364 (2007/10/03)
Novel 3-hydroxypyridin-4-one containing tridentate ligands were synthesised and their physicochemical properties characterised, including ionisation constants and stoichiometric titration with Fe(III). There is an urgent demand for orally active iron chelators with potential for the treatment of thalassaemia. In principle, tridentate ligands are likely to be more kinetically stable than bidentate molecules, but to date no satisfactory molecules have been identified. Fe(III) stability constants were assessed by competition with the hexadentate ligand EDTA. In all cases no evidence was found for a tridentate mode of iron chelation; instead the ligands behaved as bidentate hydroxypyridinones. As a consequence they provide no advantage over the more simple alkyl hydroxypyridinones.
Monitoring of phthalic acid monoesters in river water by solid-phase extraction and GC-MS determination
Suzuki,Yaguchi,Suzuki,Suga
, p. 3757 - 3763 (2007/10/03)
An analytical method for monitoring 10 phthalic acid monoesters in river water was investigated by solid-phase extraction, methylation with diazomethane, and GC-MS. Two cartridge-type solid phases packed with octadesyl-coated silica (C18) and styrenedivinyl polymer (PS-2) and one disk-type solid phase made from octadesyl-coated styrene-divinylbenzene polymer (SDB-XD) were investigated in solid-phase extraction. PS-2 gave the highest recoveries of the three solid phases, and recoveries of more than 80% of the monoesters in filtered water samples were obtained at pH 2 to 3 with PS-2 at the spiked level of 0.1 μg L-1, except for monomethyl-phthalate (MMP), in which more than 72% of the monoesters were recovered. For the monoesters in the suspended solids (SS), an acidic methanol extract of SS was added to purified water acidified to pH 2, and the monoesters were extracted with PS-2. The recoveries of the monoesters in SS were more than 80%, but the recoveries of MMP were more than 57%. The method detection limit (MDL) of each phthalic acid monoester in 500 mL of water sample and in 2 mg of dry weight of SS ranged from 0.010 to 0.030 μg L-1 and from 1 to 11 μg g-1 respectively. Monitoring of phthalic acid monoesters in the Tama River in Tokyo was conducted every month from March 1999 to February 2000 using the present method. MMP, mono-n-butyl-phthalate (MBP), and mono-(2-ethylhexyl)-phthalate (MEHP) were detected at concentrations of 0.030-0.0340, 0.010-0.480, and 0.010-1.30 μg L-1. respectively, in the filtered water samples but were not detected in SS. Dimethyl-phthalate (DMP), di-n-butyl-phthalate (DBP), and di-(2-ethylhexyl)-phthalate (DEHP) were detected in the river water at concentrations of 0.010-0.092, 0.008-0.540, and 0.013-3.60 μg L-1, respectively. Diethyl-, di-iso-butyl-, and benzylbutyl-phthalates were also detected at concentrations of nanograms per liter, whereas the corresponding monoesters did not appear. The concentrations of MBP and MEHP in the river water were slightly lower than those of the corresponding diesters at the majority of sampling sites and sampling times.
Preferential hydrogenolysis of NAP esters provides a new orthogonal protecting group strategy for carboxylic acids
Gaunt, Matthew J.,Boschetti, Carlos E.,Yu, Jinquan,Spencer, Jonathan B.
, p. 1803 - 1806 (2007/10/03)
Selective hydrogenolysis of 2-naphthylmethyl (NAP) esters in the presence of a benzyl ester has been observed with a wide range of dicarboxylic acids. Orthogonal deprotection of NAP esters with challenging substrates can be achieved if the other carboxylic acids in the molecule are protected with 4-trifluoromethyl benzyl group instead of benzyl groups.
Prop-2-ynyl as a protective group for carboxylic acids: A mild method for the highly selective deprotection of prop-2-ynyl esters using tetrathiomolybdate
Ilankumaran, Palanichamy,Manoj,Chandrasekaran, Srinivasan
, p. 1957 - 1958 (2007/10/03)
It is shown that prop-2-ynyl esters are useful protecting groups for carboxylic acids and that they are selectively deprotected in the presence of other esters on treatment with tetrathiomolybdate under mild conditions.
