| abstract |
A compound of formula I: in which R1 and R2 independently represent a group selected from: (i) C3-8 cycloalkyl; (ii) hydrogen; (iii) aryl2CHCH2 -; (iv) C3-8cycloalkylC1-6alkyl-; (v) C1-8alkyl-; (vi) C1-6alkylalkyl-; (vii) R4 R5 N-C1-6alkyl-; (viii) C1-6 alkyl -CH (CH2 OH) -; (ix) C1-5 arylalkyl -CH (CH2 OH) -; (x) C1-5-arylalkyl-C (CH2 OH) 2 -; (xi) C3-8 cycloalkyl independently substituted by one or more groups - (CH2) p R6; (xii) H2 NC (= NH) NH C1-6alkyl -; (xiii) a group of the formula or such a group in which a methylene carbon atom is adjacent to X, or both, if such exists, is substituted for methyl; (xiv) -C1-6alkyl -OH; (xv) -haloC1-8alkyl; (xvi) a group of formula (xvii) aryl; R3 represents methyl, ethyl or isopropyl, R4 and R5 independently represent hydrogen, C1-6 alkyl, aryl, arylalkyl C1-6 - or NR4 R5 together can represent pyrrolidinyl, piperidinyl, morpholinyl; acetidinyl, accepinyl, ... |