- Synthesis of 5,6-disubstituted thieno[2,3-d]pyrimidines from 4-chloropyrimidines
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Facile reaction sequences for the preparation of 5,6-disubstituted thieno[2,3-d]pyrimidines starting with 4-chloropyrimidines have been developed. 4-Chloro-6-methoxypyrimidines were aroylated at the 5-positions via lithiation with LDA and subsequent treatment with benzaldehyde or N-methoxy- Nmethylbenzamides to give aryl(4-chloro-6-methoxypyrimidin-5-yl)methanones. These pyrimidinyl ketones were transformed in one-pot into 5,6-disubstituted 4-methoxythieno[2,3-d]pyrimidines by a successive treatment with sodium sulfide, BrCH2EWGs, and sodium hydride. Lithiation of 4,6-dichloro-2-(methylsulfanyl) pyrimidine at the 5-position was followed by treatment with tertiary formamides to give 4-chloro-6-(dialkylamino)pyrimidine-5-carboxaldehydes, which could be transformed into 5,6-disubstituted 4-(dialkylamino)thieno[2,3-d]pyrimidines via aryl[4-chloro-6-(dialkylamino)-pyrimidin-5-yl]methanones using the same one-pot thiophene ring forming sequence.
- Kobayashi, Kazuhiro,Suzuki, Teruhiko,Kozuki, Taketoshi,Matsumoto, Naoki,Hiyoshi, Hidetaka,Umezu, Kazuto
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experimental part
p. 1405 - 1416
(2012/08/07)
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- Competitive formation of condensed azines and dihydropyridines in the reaction of ethyl 3,3-diaminoacrylate with o-halo carbaldehydes
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The reaction of ethyl 3,3-diaminoacrylate with quinoline-3-carbaldehydes and 3-nitrobenzaldehydes to give a dihydropyridine and condensed azine has been studied with respect to the number and reactivity of the halogen atoms in an ortho position to the formyl groups. For the series of quinoline-3-carbaldehydes it was found that the reaction course is determined by the number of chlorine atoms. 2-and 4-Chloroquinoline-3-carbaldehydes give dihydropyridines and a benzo[c][2,7-]naphthyridine is formed in the reaction with 2,4- dichloroquinoline-3-carbaldehyde. The main products in the case of nitrobenzaldehydes are dihydropyridines which points the deciding influence of the low electrophilicity of aromatic ring.
- Eliseev Jr.,Dar'in,Selivanov,Lobanov,Potekhin
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experimental part
p. 442 - 450
(2009/04/04)
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- New method for the synthesis of thieno[2,3-d]pyrimidines
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The reaction of 5-formyl-4-thiocyanatopyrimidines with nitromethane was studied under various conditions. The reaction was found unexpectedly to proceed with closure of a thiophene ring to give thieno[2,3-d]pyrimidines. The use of ammonium acetate as the catalyst leads to a side reaction involving closure of an isothiazole ring to give isothiazolo[5,4-d]pyrimidines. X-ray diffraction crystallographic analysis was used to confirm the structure of thieno[2,3-d]pyrimidine.
- Ryabova,Evstratova,Makarov,Tafeenko,Granik
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p. 1352 - 1358
(2007/10/03)
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- Synthesis of isoxazolo [3,4-d]pyrimidines from 6-chloropyrimidine-5-carbaldehydes
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4-Dialkylamino-6-chloro-2-methylthiopyrimidine-5-carbaldehydes with sodium azide in dimethylformamide underwent ring closure reaction to form the corresponding isoxazolo[3,4-d]pyrimidines.
- Kaminskas,Dailide,Tumkevicius
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p. 725 - 728
(2007/10/03)
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