- Electrochemical Nitration with Nitrite
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Aromatic nitration has tremendous importance in organic chemistry as nitroaromatic compounds serve as versatile building blocks. This study represents the electrochemical aromatic nitration with NBu4NO2, which serves a dual role as supporting electrolyte and as a safe, readily available, and easy-to-handle nitro source. Stoichiometric amounts of 1,1,1-3,3,3-hexafluoroisopropan-2-ol (HFIP) in MeCN significantly increase the yield by solvent control. The reaction mechanism is based on electrochemical oxidation of nitrite to NO2, which initiates the nitration reaction in a divided electrolysis cell with inexpensive graphite electrodes. Overall, the reaction is demonstrated for 20 examples with yields of up to 88 %. Scalability is demonstrated by a 13-fold scale-up.
- Blum, Stephan P.,Nickel, Christean,Sch?ffer, Lukas,Karakaya, Tarik,Waldvogel, Siegfried R.
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p. 4936 - 4940
(2021/10/25)
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- Method for synthesizing 4-chloro-2, 5-dimethoxynitrobenzene by using microreactor
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The invention relates to a method for synthesizing 4-chloro-2, 3, 5-tetramethylpiperidine by using a microreactor. According to the method, intermediate 2, 5-dimethoxychlorobenzene of 4-chloro-2, 5-dimethoxynitrobenzene and nitric acid are used as raw materials, 4-chloro-2, 5-dimethoxynitrobenzene is synthesized through the microreactor, in the reaction process, the mass fraction of nitric acid is50%-95%, and the mass fraction of a 2, 5-dimethoxychlorobenzene solution is 15%-50%; the feeding molar ratio of nitric acid to 2, 5-dimethoxychlorobenzene is (1.0-1.5): 1, the reaction temperature is50-85 DEG C, the feeding temperature is not higher than 50 DEG C, and the reaction retention time is 30-120 seconds. According to the method, on one hand, the process conditions such as the materialratio and the reaction temperature are accurately controlled, the dosage of nitric acid is reduced, the method is environmentally friendly, the conversion rate of 2, 5-dimethoxychlorobenzene reaches 99.98%, and the yield of 4-chloro-2, 5-dimethoxynitrobenzene reaches 99.5% or above; on the other hand, the key problems of corrosivity of nitric acid, difficulty in controlling the reaction temperature, poor mass and heat transfer effect, poor safety and the like in the conventional synthesis process are solved, and the reaction risk is low; strong operability.
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Paragraph 0021-0028
(2020/12/05)
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- Synthetic studies on lactonamycins: Synthesis of the model BCDEF aglycon
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The lactonamycin model aglycon 4 was synthesized from the trihalogenated benzene derivative 10. Ethynyltetraol 6 was prepared from 10 via carbon elongations, oxidative demethylation, a cycloaddition reaction with the diene derived from homophthalic anhydride, and dihydroxylation. Final E- and F-ring constructions from 6 were realized via a palladium-catalyzed cyclization-methoxycarbonylation, a stereoselective methanol addition, and lactonization, leading to the production of 4.
- Watanabe, Kana,Iwata, Yusuke,Adachi, Satoshi,Nishikawa, Tomoyuki,Yoshida, Yuko,Kameda, Shunsuke,Ide, Mitsuaki,Saikawa, Yoko,Nakata, Masaya
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supporting information; experimental part
p. 5573 - 5579
(2010/11/05)
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- A concise total synthesis of (±)-A80915G, a member of the napyradiomycin family of antibiotics
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(±)-A80915G, a member of the napyradiomycin family of antibiotics, has been synthesized from 1-amino-2,5-dimethoxy-4-nitrobenzene via the sequential palladium-catalyzed cross-coupling reactions (the Stille reaction) of aryl halides with allyltins and the Diels-Alder reaction of the chloroquinone with the Danishefsky-Brassard diene.
- Takemura, Shunji,Hirayama, Aya,Tokunaga, Junko,Kawamura, Fumie,Inagaki, Kyoko,Hashimoto, Kimiko,Nakata, Masaya
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p. 7501 - 7505
(2007/10/03)
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- Synthesis of quinones from hydroquinone dimethyl ethers. Oxidative demethylation with cobalt(III) fluoride
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The oxidative demethylation of 1,4-dimethoxynaphthalene and 1,4- dimethoxybenzene derivatives with cobalt(III) fluoride proceeded in good to excellent yield to afford the corresponding naphthoquinone and benzoquinone derivatives.
- Tomatsu, Ayumi,Takemura, Syunji,Hashimoto, Kimiko,Nakata, Masaya
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p. 1474 - 1476
(2007/10/03)
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- NITRIC ACID ON SILICA GEL: A USEFUL NITRATING REAGENT FOR ACTIVATED AROMATIC COMPOUNDS
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Phenols and arylmethyl ethers are rapidly mononitrated by nitric acid adsorbed in silica gel at room temperature in high yields.
- Tapia, Ricardo,Torres, Glenda,Valderrama, Jaime A.
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p. 681 - 688
(2007/10/02)
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