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21.
A convenient synthesis of 1-alkyl-2-chloro-1H-indole-3-carbaldehyde oximes(5a―5d) and 1-alkyl-2-phenoxy-1H-indole-3-carbaldehyde oximes(6a―6d) from 2-indolone was completed via the Vilsmeier-Haack reac-tion,with N-alkylation and oximation as the key steps.An improved one-pot method for the synthesis of 1-alkyl-2-alkoxy-1H-indole-3-carbaldehyde oximes(7a―7h) from 1-alkyl-2-chloro-1H-indole-3-carbaldehydes(3a―3d) was described.The Williamson reactions and esterification reactions were performed and the oxime-... 相似文献
22.
We recount several unexpected results observed in the course of our work toward the synthesis of welwitindolinone alkaloids. The surprising results provide an opportunity to refine one’s understanding of the interplay between chemical structure and reactivity. 相似文献
23.
A modular and efficient synthesis of the biologically significant C-methylisoflavones isosideroxylin(1),6,8-dimethylgenistein(2) and their analogues(3-8) is established for the first time.The synthesis is realized in 7-8 steps in overall yields of 16%-24%from commercially inexpensive phloroglucinol and features a high yielding Vilsmeier-Haack reaction,Friedel-Crafts acylation,Gammill's protocol and Suzuki coupling as the pivotal transformations.Next,these compounds evaluated for their inhibitory potency on the production of nitric oxide(NO) in lipopolysaccharide(LPS)-activated RAW-264.7 cells as an indicator of anti-inflammatory activity.The results showed that all the compounds decreased NO production in a dose-dependent manner without marked cytotoxicity and IC_(50) values are found in the range of 10.17-33.88 μmol/L.Of note,compounds 3 followed by 1,7 and 8 show comparable inhibitory activity with positive control(N-monomethyl-L-arginine,L-NMMA). 相似文献
24.
Nidhin PaulShanmugam Muthusubramanian 《Tetrahedron letters》2011,52(29):3743-3746
Vilsmeier’s reagent treatment of substituted diphenacyl sulfides or diphenacyl disulfides has led to the formation of a series of benzfused 3-chlorothiophene-2-carbaldehydes by a Domino Vilsmeier-Haack reaction/ring closure sequence, opening a new route for the synthesis of 3-chlorobenzo[b]thiophene-2-carbaldehydes and their benzfused analogues. A plausible mechanism has been proposed. 相似文献
25.
Enhydroxylaminones—2,2-dimethyl-2,4-dihydro-3H-pyrrol-3-on-1-oxides were shown to give various chlorinated products in the Vilsmeier-Haack reaction. The general sequence of the reaction steps is determined and the extent of the reaction was shown to be strongly dependent on the substrate structure. 相似文献
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27.
V. A. Valiullin T. E. Ivakhnenko G. S. Borodkin Sh. G. Mkoyan S. M. Aldoshin E. P. Ivakhnenko 《Russian Chemical Bulletin》2006,55(5):860-864
Formylation of N-phthaloylglycine with the POCl3-DMF system afforded N,N,N′, N′-tetramethyl-2-(N-phthaloyl)vinamidinium perchlorate (2). X-ray diffraction study showed that molecule 2 is planar and contains two equivalent nitrogen atoms in the three-carbon vinamidinium fragment. Salt 2 undergoes transamination with primary aromatic amines to give the corresponding bis-azomethines. The reactions with hydrazines
produce substituted 4-aminopyrazoles.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 832–835, May, 2006. 相似文献
28.
The reaction of 2- and 4-hydroxypyrimidines containingortho- andpara-hydroxyphenyl substituents with Vilsmeier-Haack reagents generatedin situ from DMF and SOCl2 or POCl3 results in the chemoselective replacement of the heterocyclic hydroxyl group by chlorine and formylation of the phenolic hydroxyl group. Aryl formates are hydrolyzed under the conditions of their isolation to give the corresponding phenols, especially if the pyrimidyl fragment isortho to the formyloxy group.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1105–1108, June, 1993. 相似文献
29.
C.V. Asokan Ajith Dain Thomas Ann Maria Jose K.C. Lethesh M. Prasanth K.U. Krishanraj 《Tetrahedron letters》2007,48(32):5641-5643
Simple enolizable ketones such as acetophenones and benzalacetones were treated with malononitrile under Vilsmeier-Haack reaction conditions to afford 2-chloronicotinonitriles. The reaction proceeds via a one-pot chloromethyleneiminium salt mediated three-component reaction followed by sequential cyclization and aromatization under Vilsmeier-Haack reaction conditions. 相似文献
30.
Regioselective formylation behavior has been found in the reaction of pyrazolo[3,4-b]pyridines and pyrazolo[1,5-a]pyrimidines via Vilsmeier-Haack conditions. While the 4,5- and 6,7-dihydro derivatives afforded pyrazolo[3,4-b]pyridine-5-carbaldehydes and 4,7-dihydropyrazolo[1,5-a]pyrimidine-3,6-dicarbaldehydes, respectively, the aromatic analogs rendered the pyrazolo[1,5-a]pyrimidine-3-carbaldehyde only, and no reaction took place at the pyrazolopyridine derivatives. 相似文献