- Br?nsted Acid Mediated Nucleophilic Functionalization of Amides through Stable Amide C?N Bond Cleavage; One-Step Synthesis of 2-Substituted Benzothiazoles
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We have developed a Br?nsted acid mediated synthetic method to directly cleave stable amide C?N bonds by a variety of alcohol and amine nucleophiles. Reverse reactivity was observed and alcoholysis of amides by activated primary and secondary benzylic, and propargylic alcohols have been achieved instead of the expected nucleophilic substitution of alcohols. As an application, 2-substituted benzothiazole derivatives have been synthesized in one pot employing 2-aminothiophenol as nucleophile.
- Biswas, Srijit,Biswas, Subrata,Duari, Surajit,Elsharif, Asma M.,Maity, Srabani,Roy, Arnab
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supporting information
p. 3569 - 3572
(2021/07/22)
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- Oxidative Decarboxylation Enables Chemoselective, Racemization-Free Esterification: Coupling of α-Ketoacids and Alcohols Mediated by Hypervalent Iodine(III)
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An α-ketoacid could be converted into a reactive acylating agent by treatment with hypervalent iodine(III) species, and in so doing, we discovered a novel decarboxylative acylation of alcohols that affords a variety of esters in excellent yields. The esterification has been applied to a sterol bearing a free carboxylic acid and shows unique chemoselectivity. The procedure is racemization-free and operates under mild conditions.
- Nanjo, Takeshi,Kato, Natsuki,Takemoto, Yoshiji
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supporting information
p. 5766 - 5769
(2018/09/12)
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- Efficient and selective esterification of aromatic aldehydes with alcohols (1:1) using air as the simplest available oxidant and KCN
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A new and efficient method is described for the oxidative esterification of aromatic aldehydes with different types of alcohols such as primary, secondary, benzylic, allylic and cyclic alcohols and phenols using air as the simplest available oxidant and potassium cyanide in DMF under neutral conditions in high yields. The present method esterifies aldehydes with alcohols in 1:1 molar ratio with excellent chemoselectivity and avoids the use of an external oxidant beside 02 from air.
- Aghapour, Ghasem,Karimzadeh, Maryam
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p. 1013 - 1018
(2017/11/10)
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- A microwave-assisted highly practical chemoselective esterification and amidation of carboxylic acids
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The ubiquitousness of esters and amide functionalities makes their coupling reaction one of the most sought-after organic transformations. Herein, we have described an efficient microwave-assisted synthesis of esters and amides. Soluble triphenylphosphine, in conjugation with molecular iodine, gave the desired products without the requirement for a base/catalyst. In addition, a solid-phase synthetic route is incorporated for the said conversion, which has added advantages over solution-phase pathways, such as low moisture sensitivity, easy handling, isolation of the product by simple filtration, and reusability. In short, our method is simple, mild, green, and highly chemoselective in nature.
- Pathak, Gunindra,Das, Diparjun,Rokhum, Lalthazuala
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p. 93729 - 93740
(2016/10/21)
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- Staudinger’s phosphazene as an efficient esterifying reagent
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A new application of Staudinger’s phosphazene as an efficient esterifying reagent is reported. Staudinger’s phosphazene formed in situ by the reaction of organic mono-azide with triphenylphosphine, which is trapped by carboxylic acid, to afford amide exclusively. In contrast, interestingly the same phosphazene behaves in a different way as an efficient esterifying reagent, affording ester under a solvent-free microwave-assisted protocol wherein alcohol is added as the another component in addition to the other reactants. This discovery adds yet another new application of Staudinger’s phosphazene to synthetic chemistry.
- Dinesh, Murugan,Ranganathan, Raja,Archana, Sivasubramaniyan,Sathishkumar, Murugan,Roshan Banu, Mohamed Sulthan,Ponnuswamy, Alagusundaram
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supporting information
p. 1454 - 1460
(2016/09/14)
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- Bis azide-triphenylphosphine as a reagent for esterification at room temperature
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Modified Staudinger reaction is a well-established reaction for the amide synthesis from organic azides and carboxylic acids in the presence of phosphorous reagents. In contrary to this, it is notable that bis azide in the presence of triethylphosphite or trimethylphosphite does not afford the expected bis amides but affords the ethyl or methyl esters of the carboxylic acids respectively. This serendipitous observation when further investigated results in the discovery of bis azide-triphenylphosphine as an efficient reagent for esterification at room temperature.
- Dinesh, Murugan,Archana, Sivasubramaniyan,Ranganathan, Raja,Sathishkumar, Murugan,Ponnuswamy, Alagusundaram
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supporting information
p. 6975 - 6979
(2015/11/27)
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- From ketones to esters by a Cu-catalyzed highly selective C(CO)-C(alkyl) bond cleavage: Aerobic oxidation and oxygenation with air
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The Cu-catalyzed aerobic oxidative esterification of simple ketones via C-C bond cleavage has been developed. Varieties of common ketones, even inactive aryl long-chain alkyl ketones, are selectively converted into esters. The reaction tolerates a wide range of alcohols, including primary and secondary alcohols, chiral alcohols with retention of the configuration, electron-deficient phenols, as well as various natural alcohols. The usage of inexpensive copper catalyst, broad substrate scope, and neutral and open air conditions make this protocol very practical. 18O labeling experiments reveal that oxygenation occurs during this transformation. Preliminary mechanism studies indicate that two novel pathways are mainly involved in this process. (Chemical Equation Presented)
- Huang, Xiaoqiang,Li, Xinyao,Zou, Miancheng,Song, Song,Tang, Conghui,Yuan, Yizhi,Jiao, Ning
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supporting information
p. 14858 - 14865
(2014/12/11)
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- Cu-catalyzed esterification reaction via aerobic oxygenation and C-C bond cleavage: An approach to α-ketoesters
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The Cu-catalyzed novel aerobic oxidative esterification reaction of 1,3-diones for the synthesis of α-ketoesters has been developed. This method combines C-C σ-bond cleavage, dioxygen activation and oxidative C-H bond functionalization, as well as provides a practical, neutral, and mild synthetic approach to α-ketoesters which are important units in many biologically active compounds and useful precursors in a variety of functional group transformations. A plausible radical process is proposed on the basis of mechanistic studies.
- Zhang, Chun,Feng, Peng,Jiao, Ning
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supporting information
p. 15257 - 15262
(2013/11/06)
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