- Nucleophilic aromatic substitution of methyl 3-nitropyridine-4-carboxylate
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The nitro group of methyl 3-nitropyridine-4-carboxylate (1) has successfully been replaced by nitrogen, oxygen and sulphur nucleophiles by nucleophilic aromatic substitution to give the 3-azido, 3-methoxy, 3-phenoxy and 3-thiophenoxypyridine-4-carboxylate
- Holt, Jarle,Tjosa, Freddy,Bakke, Jan M.,Fiksdahl, Anne
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- ATMOSPHERE DEPENDENT PHOTOREACTION OF METHYL 4-PYRIDINECARBOXYLATE IN METHANOL. METHOXYLATION AT 3-POSITION UNDER O2 AND METHOXYLATION AND HYDROXYMETHYLATION AT 2-POSITION UNDER N2
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The UV-Irradition of methyl 4-pyridinecarboxylate in methanol under oxygen in the presence of H2SO4 brings about methoxylation at the 3-position of the pyridine ring, while under nitrogen methoxylation and hydroxymethylation occur at the 2-position.
- Sugiyama, Toru,Yagi, Kazuya,Ito, Yoko,Sugimori, Akira
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- Spin-Center Shift-Enabled Direct Enantioselective α-Benzylation of Aldehydes with Alcohols
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Nature routinely engages alcohols as leaving groups, as DNA biosynthesis relies on the removal of water from ribonucleoside diphosphates by a radical-mediated "spin-center shift" (SCS) mechanism. Alcohols, however, remain underused as alkylating agents in synthetic chemistry due to their low reactivity in two-electron pathways. We report herein an enantioselective α-benzylation of aldehydes using alcohols as alkylating agents based on the mechanistic principle of spin-center shift. This strategy harnesses the dual activation modes of photoredox and organocatalysis, engaging the alcohol by SCS and capturing the resulting benzylic radical with a catalytically generated enamine. Mechanistic studies provide evidence for SCS as a key elementary step, identify the origins of competing reactions, and enable improvements in chemoselectivity by rational photocatalyst design.
- Nacsa, Eric D.,MacMillan, David W. C.
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supporting information
p. 3322 - 3330
(2018/03/13)
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- Atmosphere Dependent Photoreaction of 4-Pyridinecarboxylic Ester in Acidic Methanolic Solutions
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The UV-irradiation of methyl 4-pyridinecarboxylate (1) in methanol under oxygen in the presence of sulfuric acid brings about methoxylation at the 3-position of the pyridine ring, while under nitrogen methoxylation and hydroxymethylation occur at the 2-position.The change of photoreactions of 1 caused by oxygen can not be explained either by the promotion of intersystem crossing by O2 or by the charge transfer interactions between 1 and O2.
- Sugiyama, Toru,Kusano, Yukari,Yagi, Kazuya,Ito, Yoko,Sugimori, Akira
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p. 1882 - 1886
(2007/10/02)
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- Synthetic Application of Lithiation Reactions: A Convenient Synthesis of 3,4-Dihydro-5-hydroxycarbostyril, 1,2,3,4-Tetrahydro-5-hydroxy-2-oxo-1,7-naphthyridine, and Methyl 3-Methoxypyridine-4-carboxylate
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3,4-Dihydro-5-hydroxycarbostyril (3), a key intermediate for a clinically used β-receptor blocking agent (1), and its 7-aza analog (4) were prepared by an acid-catalyzed cyclization of the N-pivaloylamino-esters (17 and 19), which were obtained by using o
- Tamura, Yasumitsu,Chen, Ling Ching,Fujita, Masanobu,Kita, Yasuyuki
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p. 1257 - 1262
(2007/10/02)
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