936574-08-2Relevant academic research and scientific papers
Reactions of 9-aryl-6-cyanopurines with primary amines
Al-Azmi, Amal,Anita Kumari
experimental part, p. 2245 - 2262 (2010/04/29)
Two structural isomers (9-aryl-6-cyanopurines and imidazole-4,5-dicarbonitriles) were isolated from the reaction of (Z)-N1-aryl-N2-(2-amino-1,2-dicyanovinyl)formamidines with triethyl orthoacetate or propionate. On the other hand, 9-aryl-6-cyanopurines were the only product, when triethyl orthoformate was used. The reaction of 9-aryl-6-cyanopurines with hydroxylamine hydrochloride in dichloromethane/ethanol at room temperature furnished 6-amidinopurines, while reaction with primary amines afforded pyrimido[5,4-d]pyrimidines. In addition, 9-aryl-6-cyanopurines reacted with hydrazine monohydrate under mild conditions to give 4-imino-N8-arylpyrimido[5,4-d]pyrimidines. The latter furnished novel pyrimido[4,5-e][l,2,4]triazolo[l,5-c]pyrimidines when refluxed with an excess of triethyl orthoesters. The new compounds were fully characterized and single crystal X-ray analyses have been carried out on 9-(4-methoxyphenyl)-9H-purine-6-carboximidamide and 2-methyl-1-[(E)-p-tolyliminomethyl]-1H-imidazole-4,5-dicarbonitrile.
An efficient synthesis of 7,8-dihydropyrimido[5,4-d]pyrimidines
Carvalho, M. Alice,Esperanca, Sandra,Esteves, Teresa,Proenca, M. Fernanda
, p. 1324 - 1331 (2008/09/18)
7,8-Dihydropyrimido[5,4-d]pyrimidines 4 were isolated in very good yields by treatment of 9-aryl-6-cyanopurines 1 with primary amines. Nucleophilic attack of the amine on C8 of the purine ring was followed by ring-opening of the imidazole unit, and subsequent intramolecular cyclization involving the newly formed amidine group and the cyano substituent in the pyrimidine ring produced the 7,8-dihydropyrimido[5,4-d]pyrimidine structure 4. When ammonia was used instead of primary amines, compound 4 rapidly reacted further to afford the more stable pyrimido[5,4-d]pyrimidine 6 as a result of tautomeric equilibration. The aromatic structure 6 was also isolated when purine 1a and an excess of ethanolamine were heated at reflux in methanol, and also when purine 1c was combined with an excess of (4-methoxyphenyl)-hydrazine in THF at room temperature in the presence of a catalytic amount of DBU. In both cases the product is formed by a Dimroth rearrangement of the precursor 7,8-dihydropyrimido[5,4-d]pyrimidine 4. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
