- Oxidative Alkane C?H Alkoxycarbonylation
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Directly utilizing a chemical feedstock to construct valuable compounds is an attractive prospect in organic synthesis. In particular, the combination of C(sp3)?H activation and oxidative carbonylation involving alkanes and CO gas is a promising and efficient method to synthesize carbonyl derivatives. However, due to the high C?H bond dissociation energy and low polarity of unactivated alkanes, the carbonylation of unactivated C(sp3)?H bonds still remains a great challenge. In this work, we introduce a palladium-catalyzed radical oxidative alkoxycarbonylation of alkanes to prepare numerous alkyl carboxylates. Various alkanes and alcohols were compatible, generating the desired products in up to 94 % yield. Remarkably, ethane, a constituent of natural gas, could be employed as a substrate under the standard reaction conditions. Preliminary mechanistic studies revealed a probable palladium-catalyzed radical process.
- Lu, Lijun,Shi, Renyi,Liu, Luyao,Yan, Jingwen,Lu, Fangling,Lei, Aiwen
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supporting information
p. 14484 - 14488
(2016/10/03)
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- Hydrophobic N,N-diarylammonium pyrosulfates as dehydrative condensation catalysts under aqueous conditions
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Oil-soluble N,N-diarylammonium pyrosulfates as nonsurfactant-type catalysts for the dehydrative ester condensation under aqueous conditions are described. Preheat treatment of dibasic sulfuric acid with bulky N,N-diarylamines generates water-tolerant salts of pyrosulfuric acid as active catalyst species. The present catalysts in water can also widely be applied to unusual selective esterifications and dehydrative glycosylation.
- Sakakura, Akira,Koshikari, Yoshiki,Akakura, Matsujiro,Ishihara, Kazuaki
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supporting information; experimental part
p. 30 - 33
(2012/02/14)
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- Dehydration reactions in water. Bronsted acid-surfactant-combined catalyst for ester, ether, thioether, and dithioacetal formation in water
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Dehydration reactions in water have been realized by a surfactant-type catalyst, dodecylbenzenesulfonic acid (DBSA). These reactions include dehydrative esterification, etherification, thioetherification, and dithioacetalization. In these reactions, DBSA and substrates form emulsion droplets whose interior is hydrophobic enough to exclude water molecules generated during the reactions. Detailed studies on the esterification revealed that the yields of esters were affected by temperature, amounts of DBSA used, and the substrates. Esters were obtained in high yields for highly hydrophobic substrates. On the basis of the difference in hydrophobicity of the substrates, unique selective esterification and etherification in water were attained. Furthermore, chemospecific, three-component reactions under DBSA-catalyzed conditions were also found to proceed smoothly. This work not only may lead to environmentally benign systems but also will provide a new aspect of organic chemistry in water.
- Manabe, Kei,Iimura, Shinya,Sun, Xiang-Min,Kobayashi, Shu
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p. 11971 - 11978
(2007/10/03)
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