- Photoredox-Catalyzed Benzylic Esterification via Radical-Polar Crossover
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Photoredox-catalyzed C-O bond formation reactions are reported. The decarboxylative esterification reaction allows the conversion of a variety of arylacetic acids into the corresponding benzyl carboxylates. Furthermore, the use of (diacetoxyiodo)benzene allows the conversion of the benzylic C-H bond through hydrogen atom transfer. The reactions were applied to the divergent transformation of pharmaceuticals via decarboxylative or C-H esterification reactions.
- Maeda, Bumpei,Sakakibara, Yota,Murakami, Kei,Itami, Kenichiro
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supporting information
p. 5113 - 5117
(2021/07/19)
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- Mechanochemical Palladium-Catalyzed Carbonylative Reactions Using Mo(CO)6
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Esters and amides were mechanochemically prepared by palladium-catalyzed carbonylative reactions of aryl iodides by using molybdenum hexacarbonyl as a convenient solid carbonyl source and avoiding a direct handling of gaseous carbon monoxide. Real-time monitoring of the mechanochemical reaction by in situ pressure sensing revealed that CO is rapidly transferred from Mo(CO)6 to the active catalytic system without significant release of molecular carbon monoxide.
- van Bonn, Pit,Bolm, Carsten,Hernández, José G.
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p. 2576 - 2580
(2020/02/20)
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- Esterification of Tertiary Amides by Alcohols Through C?N Bond Cleavage over CeO2
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CeO2 has been found to promote ester forming alcoholysis reactions of tertiary amides. The present catalytic system is operationally simple, recyclable, and it does not require additives. The esterification process displays a wide substrate scope (>45 examples; up to 93 % isolated yield). Results of a density functional theory (DFT) study combined with in situ FT-IR observations indicate that the process proceeds through rate limiting addition of a CeO2 lattice oxygen to the carbonyl group of the adsorbed acetamide species with energy barrier of 17.0 kcal/mol. This value matches well with experimental value (17.9 kcal/mol) obtained from analysis of the Arrhenius plot. Further studies by in situ FT-IR and temperature programmed desorption using probe molecules demonstrate that both acidic and basic properties are important, and consequently, CeO2 showed the best performance for the C?N bond cleavage reaction.
- Toyao, Takashi,Nurnobi Rashed, Md.,Morita, Yoshitsugu,Kamachi, Takashi,Hakim Siddiki,Ali, Md. A.,Touchy,Kon, Kenichi,Maeno, Zen,Yoshizawa, Kazunari,Shimizu, Ken-ichi
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p. 449 - 456
(2018/09/11)
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- Making Carbonyls of Amides Nucleophilic and Hydroxyls of Alcohols Electrophilic Mediated by SO2F2 for Synthesis of Esters from Amides
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We discovered that with the promotion of sulfuryl fluoride, the carbonyl groups of amides performed as nucleophiles while the hydroxyl groups of alcohols were activated to functionalize as electrophiles. This study displayed that the amide C-N bonds could be easily cleaved with delicate nucleophiles to form the ester C-O bonds at room temperature without using transition metals. The broad substrate scope and excellent functional group compatibility were proved with 44 examples in up to 99% yields.
- Fang, Wan-Yin,Zha, Gao-Feng,Qin, Hua-Li
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supporting information
p. 8657 - 8661
(2019/10/17)
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- Investigation of benzoyloximes as benzoylating reagents: Benzoyl-Oxyma as a selective benzoylating reagent
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Hydroxybenzotriazole (HOBt) and HOBt-derived reagents have been classified as Class I explosives, with restrictions on their transportation and storage. We explored a range of benzoylated oxime-based reagents as alternatives to benzoyloxybenzotriazole (BBTZ) for the selective benzoylation of carbohydrate polyols. Benzoylated oximes derived from 2-hydroximino-malononitrile, ethyl 2-hydroximino-2-cyanoacetate (Oxyma), and tert-butyl 2-hydroximino-2-cyanoacetate were most effective for benzoylation of a simple primary alcohol, with yields approaching that obtained for BBTZ. When applied to carbohydrate diols, the most effective reagent was identified as benzoyl-Oxyma. Benzoyl-Oxyma is a highly crystalline, readily prepared alternative to BBTZ, useful in the selective benzoylation of carbohydrate polyols.
- Burugupalli, Satvika,Shah, Sayali,Van Der Peet, Phillip L.,Arora, Seep,White, Jonathan M.,Williams, Spencer J.
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- Reactive Intermediates from the Solvolysis of Mutagenic O-Alkyl N-Acetoxybenzohydroxamates
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Mutagenic O-(para-substituted benzyl) N-acetoxybenzohydroxamates undergo acid-catalysed solvolysis in aqueous acetonitrile but three is a change in mechanism from AA11 to E1 on going from para electron-withdrawing substituents to para +M electron-donating groups.The former permit the formation of a discrete nitrenium ion intermediate whereas the latter promote a concerted elimination of a resonance stabilized benzyl carbocation.
- Bonin, Antonio M.,Glover, Stephen A.,Hammond, Gerard P.
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p. 1173 - 1180
(2007/10/02)
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