Synthesis of 5,6-Disubstituted Thieno[2,3-d]pyrimidines from 4-Chloropyrimidines
摘要:
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-N-methylbenzamides 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, BrCH(2)EWGs, 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.
Study on the cyclization of 6-arylethynylpyrimidine-5-carbaldehydes with tert-butylamine: microwave versus thermal preparation of pyrido[4,3-d]pyrimidines
Thermal and microwave initiated cyclization of 2,4-disubstituted 6-arylethynylpyrimidine-5-carbaldehydes with tert-butylamine has been studied. A novel high-yielding preparation of 2,4-disubstituted 7-arylpyrido[4,3-d]pyrimidines has been developed. The intermediate compounds were isolated and possible mechanism of the reactions is discussed. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.
Novel cyclocondensation of 2-acylethynyl-1-amino- and 2-alkoxycarbonylethynyl-1-amino-anthraquinones with pyridines