- A simple base-mediated halogenation of acidic sp2 C-H bonds under noncryogenic conditions
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(Chemical Equation Presented) A new method has been developed for in situ halogenation of acidic sp2 carbon-hydrogen bonds in heterocycles and electron-deficient arenes. Either selective monohalogenation or one-step exhaustive polyhalogenation is possible for substrates possessing several C-H bonds that are flanked by electron-withdrawing groups. For the most acidic arenes, such as pentafluorobenzene, K3PO4 base can be employed instead of BuLi for metalation/halogenation sequences.
- Do, Hien-Quang,Daugulis, Olafs
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supporting information; experimental part
p. 421 - 423
(2009/07/04)
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- In situ generation and trapping of aryllithium and arylpotassium species by halogen, sulfur, and carbon electrophiles
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(Chemical Equation Presented) A general method has been developed for in situ trapping of arylmetal intermediates by halogen, sulfur, ketone, and aldehyde electrophiles affording the functionalization of the most acidic position in arene. Pentafluorobenzene, benzothiazole, and benzoxazole can be functionalized by using K3PO4 base. For less acidic arenes, tBuOLi base is required. Arenes with DMSO pKa values of 35 or less are reactive. 2009 American Chemical Society.
- Popov, Ilya,Do, Hien-Quang,Daugulis, Olafs
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supporting information; experimental part
p. 8309 - 8313
(2010/01/16)
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- Process for the synthesis of an endothelin receptor antagonist
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The present invention relates to a practical and efficient way to synthesize the compound for the endothelin receptor antagonist involving a Grignard addition and a cyclization reaction to give a desired compound of the general formula shown below:
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- Selective deoxygenation of heteroaromatic N-oxides with olefins catalyzed by ruthenium porphyrin
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A new convenient method of deoxygenation of heteroaromatic N-oxides is described. Ruthenium porphyrin was used as a catalyst and this method expressed high yields for o-substituted pyridine N-oxides, quinoline N-oxide derivatives, acridine N-oxide, etc. under mild conditions. Moreover, nitro-, benzyloxy-, and ketone carbonyl groups, which can be affected by the usual deoxygenation methods such as catalytic hydrogenation or borane reduction, were retained.
- Nakagawa, Hiroshi,Higuchi, Tsunehiko,Kikuchi, Kazuya,Urano, Yasuteru,Nagano, Tetsuo
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p. 1656 - 1657
(2007/10/03)
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- Titanium(0) Reagents; 2. A Selective and Efficient Deoxygenation of Halogen Containing Heteroaromatic N-Oxides
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Following successful reductions of unfunctionalized heteroaromatic N-oxides by titanium(0), we applied this method to halogenated aromatic N-oxides to give the deoxygenated halogeno derivatives in 90-95percent yield.
- Malinowski, Marek,Kaczmarek, Lukasz
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p. 1013 - 1015
(2007/10/02)
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- Continuous process for the production of polybromopyridine compounds
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A continuous process for producing a polybromopyridine compound comprises admixing a polychloropyridine compound with an anhydrous water soluble solvent in a first reaction zone to form a solution of the polychloropyridine compound. Hydrogen bromide gas is introduced into the solution while maintaining the temperature in the range of from about 70° to about 140° C. to produce a solution of the polybromopyridine compound. The solution is cooled to a temperature in the range of from about 5° to about 35° C. to precipitate the polybromopyridine compound from the anhydrous solvent. The polybromopyridine compound is separated from the anhydrous solvent and the anhydrous solvent is returned to the first reaction zone. Polybromopyridine compounds of increased purity are produced in a process having reduced material, energy and operating costs. The process does not require the use of water or other co-solvents nor the distillation of the reaction product mixture.
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- Process for the manufacture of bromopyridines
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A novel process for the preparation of 2,4-dibromo-, 2,6-dibromo- and 2,4,6-tribromopyridines, and the new bromopyridines to be obtained therewith, are disclosed. The novel process comprises treating 2,4-dichloro-, 2,6-dichloro- and 2,4,6-trichloropyridines, in an anhydrous organic medium, with gaseous HBr at temperatures between 80° and 130°C, said process being both simple and economical.
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