High Yielding Methyl Esterification Catalyzed by Indium(III) Chloride

Mineno, Tomoko; Kansui, Hisao

doi:10.1248/cpb.54.918

Cited by 21 publications

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“…This fraction was therefore treated with indium(III) chloride in MeOH, as in the case of pharbitin. 16) The treated fraction exhibited a number of separate spots in TLC on silica gel. This treated fraction was successively subjected to Diaion HP20, Sephadex LH-20, silica gel, and Chromatorex ODS column chromatography, and HPLC on octadecyl silica (ODS), to afford five compounds, temporarily referred to as QM-1 (1)-QM-5 (5).…”

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confidence: 99%

“…10) However, no pure convolvulin has thus far been isolated, and chemical studies had been confined only to characterization of the component organic acids and glycosidic acids afforded by alkaline hydrolysis of mixtures of convolvulins. [11][12][13][14][15] We recently reported the isolation and structural elucidation of seven acylated glycosidic acid methyl ester monomers that were generated by treatment of the crude convolvulin fraction (named pharbitin) from Pharbitis Semen using indium(III) chloride in methanol (MeOH), 16) which was reported by Mineno and Kansui 17) to be a catalyst for mild methyl esterification of carboxylic acids.…”

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Three Acylated Glycosidic Acid Methyl Esters and Two Acylated Methyl Glycosides Generated from the Convolvulin Fraction of Seeds of Quamoclit pennata by Treatment with Indium(III) Chloride in Methanol

et al. 2013

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Treatment of the ether-insoluble resin glycoside (convolvulin) fraction from seeds of Quamoclit pennata (Convolvulaceae) with indium(III) chloride in methanol provided three oligoglycosides of hydroxy fatty acid (glycosidic acid) methyl esters and two methyl glycosides, which were partially acylated by a glycosidic acid, 7S-hydroxydecanoic acid 7-O-β-D-quinovopyranoside (quamoclinic acid B) and/or two organic acids, (E)-2-methylbut-2-enoic (tiglic) acid and/or 3R-hydroxy-2R-methylbutyric (nilic) acid. Their structures were elucidated on the basis of spectroscopic data and chemical conversions.

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confidence: 99%

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Three Acylated Glycosidic Acid Methyl Esters and Two Acylated Methyl Glycosides Generated from the Convolvulin Fraction of Seeds of Quamoclit pennata by Treatment with Indium(III) Chloride in Methanol

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“…[22][23][24][25] The authors have recently developed a practical approach to tetrahydropyranylation and depyranylation of various alcohols using indium(III) triflate.…”

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confidence: 99%

“…[22][23][24][25] The authors have recently developed a practical approach to tetrahydropyranylation and depyranylation of various alcohols using indium(III) triflate. 26) It is worth noting that with the same catalyst, the reactions proceed in directions of both protection and deprotection.…”

Section: Notesmentioning

confidence: 99%

One-Step Transformation of Tetrahydropyranyl Ethers Using Indium(III) Triflate as the Catalyst

Mineno

Nikaido

Kansui

2009

CHEMICAL & PHARMACEUTICAL BULLETIN

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NotesTetrahydropyranyl (THP) group is a well-utilized moiety, mainly as a tool to protect alcohol units due to its feasibility of installation and low cost. Stirring the free alcohols with 3,4-dihydro-2H-pyran (DHP) under acidic conditions can easily produce THP-protected alcohols.1-8) Also, THP-protected alcohols are generally stable under a wide range of reaction conditions and reagents, such as metal hydrides, alkyllithiums, Grignard reagents, and catalytic hydrogenation. O, 19,20) and CuSO 4 · 5H 2 O, 21) has also been reported.Previously, we have reported a couple of convenient reaction methods using indium or indium-related reagents. [22][23][24][25] The authors have recently developed a practical approach to tetrahydropyranylation and depyranylation of various alcohols using indium(III) triflate.26) It is worth noting that with the same catalyst, the reactions proceed in directions of both protection and deprotection. In the presence of a catalytic amount of indium(III) triflate, protection of alcohols is carried out using CH 2 Cl 2 as the solvent, whereas deprotection uses MeOH/H 2 O as the solvent. Kamal et al. also reported that tetrahydropyranylation can be controlled using catalytic aluminum(III) triflate. 27) Another report has shown the cleavage of THP ethers using titanium(III) triflate in good yields.28) According to our earlier experiments, indium(III) triflate was revealed to be an efficient catalyst for the transformation of THP ethers into their corresponding acetates. In further intensive work, we have developed a useful transforming reaction of THP ethers using various anhydride moieties with indium(III) triflate as the catalyst. Herein, we report the details of this one-step transformation. Results and DiscussionTHP-protected benzyl alcohol and N-(2-hydroxyethyl)-phthalimide were used as the starting materials. First, the suitability of the catalysts was examined by reactions with acetic anhydride (Chart 1). In both cases, the reaction proceeded and produced excellent yields in a shorter time when indium(III) triflate was employed as the catalyst (Table 1, entries 1 and 3), as compared with indium(III) chloride (Table 1, entries 2 and 4). Giving the satisfactory results with indium(III) triflate, we then expanded our investigation to the other types of anhydrides. The reactions were carried out with THP-protected benzyl alcohol, N-(2-hydroxyethyl)phthalimide, and a wide range of anhydrides (Chart 2).As expected, the reactions with another aliphatic anhydride of isobutyric anhydride generated similar satisfactory results (Table 2, entries 1 and 7). In the case of benzoic anhydride, the reaction required an extended period of time, although acceptable results were obtained (Table 2, entries 2 and 8). With the exception of entry 5, these conditions were then applied to the cyclic anhydrides, and the reactions produced entirely poor yields. These results were presumably due to the low reaction temperature. When reactions were resumed at reflux using THF as the solvent, good to excellent out...

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“…10,11) In addition, we reported the structures of seven glycosidic acids, quamoclinic acids B, C, D, E, F, G, and H, and six organic acids, isobutyric, 2S-methylbutyric, (E)-2-methylbut-2-enoic (tiglic), 2R-methyl-3R-hydroxybutyric (2R,3R-nilic), 7S-hydroxydecanoic, and 7S-hydroxydodecanoic acids obtained upon alkaline hydrolysis of the crude convolvulin fraction of the seeds. 12,13) However, despite numerous attempts, isolation of pure resin glycosides from the crude convolvulin fraction 11) of the seeds of Q. pennata had thus far been unsuccessful, because the crude convolvulin fraction show tailing or broad peaks in TLC and HPLC, until now. Previous results suggested that resin glycosides in the crude convolvulin fraction possessed at least one carboxyl group.…”

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Four New Acylated Glycosidic Acid Methyl Esters Isolated from the Convolvulin Fraction of Seeds of Quamoclit pennata after Treatment with Indium(III) Chloride in Methanol

et al. 2014

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High Yielding Methyl Esterification Catalyzed by Indium(III) Chloride

Cited by 21 publications

References 14 publications

Three Acylated Glycosidic Acid Methyl Esters and Two Acylated Methyl Glycosides Generated from the Convolvulin Fraction of Seeds of <i>Quamoclit pennata</i> by Treatment with Indium(III) Chloride in Methanol

Three Acylated Glycosidic Acid Methyl Esters and Two Acylated Methyl Glycosides Generated from the Convolvulin Fraction of Seeds of <i>Quamoclit pennata</i> by Treatment with Indium(III) Chloride in Methanol

One-Step Transformation of Tetrahydropyranyl Ethers Using Indium(III) Triflate as the Catalyst

Four New Acylated Glycosidic Acid Methyl Esters Isolated from the Convolvulin Fraction of Seeds of <i>Quamoclit pennata</i> after Treatment with Indium(III) Chloride in Methanol

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