Pyrimidines. Part XVI. Syntheses of bipyrimidinyls and of halogeno- and amidino-pyrimidines

Abstract

The following bipyrimidinyls and related biaryls have been prepared: 6,6′-dimethyl-2,2′-diphenyl-4,4′-bipyrimidinyl, 2,2′-diphenyl-5,5′-bipyrimidinyl, 2,2′-bismethylthio-5,5′-bipyrimidinyl, 2,2′,-6,6′-tetramethyl-4,4′-bipyrimidinyl, 6-methyl-2-(3-pyridyl)pyrimidin-4-ol, 4-hydroxy-6,6′-dimethyl-2′-phenyl-2,4′-bipyrimidinyl, 5-nitro-2-phenyl-4,2′-bipyrimidinyl. They were made using the Ullmann and the Busch biaryl syntheses, and also by direct condensation of aryl amidines with β-dicarbonyl compounds. The preparations of the intermediate chlorobromo-, and iodo-pyrimidines and pyrimidine amidines are described. In some cases the Busch reaction of halogenopyrimidines gave either the dehalogenated pyrimidine or the methoxypyrimidine. The Busch reaction of 5-bromo-2-phenylpyrimidine-4-carboxylic acid gave 2-phenylpyrimidine-4-carboxylic acid which was also prepared by the oxidation of 4-methyl-2-phenylpyrimidine. The action of copper bronze in boiling cymene on 4-methyl-6-phenylpyrimidine-2-thiol gave the dipyrimidinyl sulphide which was also synthesised by another route.