- Cobalt-catalyzed C[sbnd]H activation/C[sbnd]O formation: Synthesis of benzofuranones
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Herein, C[sbnd]H activation/C[sbnd]O formation reaction using novel cobalt catalytic system is reported. This reaction was given benzofuranones in moderate to excellent yields at room-temperature under air reaction conditions. The introduced strategy is efficient and low-cost method to synthesized benzofuranones from α,α-disubstitution acetic acid.
- Hajipour, Abdol R.,Khorsandi, Zahra
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- Palladium(II)-Catalyzed C(sp2)-H Carbonylation of Sterically Hindered Amines with Carbon Monoxide
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A palladium-catalyzed, amine-directed C(sp2)-H carbonylation of α,α-disubstituted benzylamine under 1 atm of CO for the facile synthesis of sterically hindered benzolactam has been developed. The key to success is the use of 2,2,6,6-tetramethyl-1-piperidinyloxy as the crucial sole oxidant. The synthetic utility of this transformation has been demonstrated by the first concise synthesis of the natural product spiropachysin-20-one.
- Cheng, Xiu-Fen,Wang, Tao,Li, Yan,Wu, Yun,Sheng, Jie,Wang, Rui,Li, Chao,Bian, Kang-Jie,Wang, Xi-Sheng
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supporting information
p. 6530 - 6533
(2018/10/20)
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- Amide-Directed C?H Sodiation by a Sodium Hydride/Iodide Composite
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A new protocol for amide-directed ortho and lateral C?H sodiation is enabled by sodium hydride (NaH) in the presence of either sodium iodide (NaI) or lithium iodide (LiI). The transient organosodium intermediates could be transformed into functionalized aromatic compounds.
- Huang, Yinhua,Chan, Guo Hao,Chiba, Shunsuke
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supporting information
p. 6544 - 6547
(2017/05/29)
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- Decarboxylative fluorination of aliphatic carboxylic acids via photoredox catalysis
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The direct conversion of aliphatic carboxylic acids to the corresponding alkyl fluorides has been achieved via visible light-promoted photoredox catalysis. This operationally simple, redox-neutral fluorination method is amenable to a wide variety of carboxylic acids. Photon-induced oxidation of carboxylates leads to the formation of carboxyl radicals, which upon rapid CO2-extrusion and F? transfer from a fluorinating reagent yield the desired fluoroalkanes with high efficiency. Experimental evidence indicates that an oxidative quenching pathway is operable in this broadly applicable fluorination protocol.
- Ventre, Sandrine,Petronijevic, Filip R.,Macmillan, David W. C.
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supporting information
p. 5654 - 5657
(2015/05/20)
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- Direct lactonization of 2-arylacetic acids through Pd(II)-catalyzed C-H activation/C-O formation
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Palladium-catalyzed direct lactonization of 2-arylacetic acids through a reaction sequence that includes C-H activation/C-O formation is reported. This method provides a concise and efficient pathway to synthesize fully functionalized benzofuranone derivatives, which are highly relevant to bioactive natural and synthetic products.
- Yang, Mingyu,Jiang, Xingyu,Shi, Wen-Juan,Zhu, Qi-Lei,Shi, Zhang-Jie
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p. 690 - 693
(2013/04/10)
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- An improved chemo-enzymatic synthesis of 1-β-O-acyl glucuronides: Highly chemoselective enzymatic removal of protecting groups from corresponding methyl acetyl derivatives
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(Chemical Equation Presented) An improved and widely applicable chemo-enzymatic method for the synthesis of a series of 1-β-O-acyl glucuronides 5a-f has been developed from the corresponding methyl acetyl derivatives 3a-f, which were stereospecifically synthesized from cesium salts of carboxylic acids 1a-f and methyl 2,3,4-tri-O-acetyl-1-bromo-1-deoxy-α-D- glucopyranuronate (2). Chemoselectivity of lipase AS Amano (LAS) in the hydrolytic removal of O-acetyl groups of 3a-f to provide methyl esters 4a-f was influenced by the nature of their 1-β-O-acyl groups; high selectivity was evident only for 3b and 3f. Carboxylesterase from Streptomyces rochei (CSR), newly screened as an alternative to LAS, showed much greater chemoselectivity toward the O-acetyl groups than LAS; 3a, 3d, and 3e were chemoselectively hydrolyzed only by CSR. The combination of CSR with LAS yielded better results in the hydrolysis of 3c and 3f than did single usage of CSR. Final deprotection of the methyl ester groups of 4a-f to provide 5a-f was chemoselectively achieved by using lipase from Candida antarctica type B (CAL-B) as well as esterase from porcine liver (PLE), although CAL-B possessed higher chemoselectivity and catalytic efficiency than did PLE. CSR also exhibited high chemoselectivity in the synthesis of (S)-naproxen 1-β-O-acyl glucopyranoside (7) from its 2,3,4,6-tetra-O-acetyl derivative 6.
- Baba, Akiko,Yoshioka, Tadao
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p. 9541 - 9549
(2008/03/27)
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- HETEROAROMATIC RING COMPOUNDS
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Heteroaromatic ring compounds or pharmaceutically acceptable salts thereof, which have excellent characteristics and have strong curative effects to immuno-imbalance and choronic inflammation. Representative is the compound of the formula:
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