| abstract |
Xanthines of general formula (I), wherein R1 represents a straight or branched chain alkyl, alkenyl or alkynyl group of 3-6 carbon atoms, and R2 and R3, which may be the same or different, each represent hydrogen or halogen or a methyl, methoxy. nitro or trifluoromethyl group or R2 and R3 together form a methylenedioxy or ethylenedioxy group; with the proviso that R2 and R3 are not both hydrogen; and pharmacologically acceptable salts thereof with an alkali metal base or a nitrogen base containing organic base, are bronchodilators making them of value in treating asthma and vasodilators making them of interest in treating angina, hypertension, congestive heart failure and multi-infarct dementia. The compounds are also of use in combatting other conditions where inhibition of PDE type IV is thought to be beneficial. The compounds can be prepared by treating the corresponding 6-amino uracil with sodium nitrite and formic acid in an excess of formamide and adding sodium dithionate to reduce the resulting 6-amino-5-nitroso compound to give the 5,6-diamino compound that ring closes with the excess of formamide. |