Abstract: A thiazole compound represented by general formula (I), wherein R is hydrogen atom, a hydroxy group, a straight or branched C.sub.1 -C.sub.6 lower alkyl group, a C.sub.1 -C.sub.4 lower alkoxy group, phenyl group, a phenyl group having one to three substituents selected from a group consisting of a C.sub.1 -C.sub.4 lower alkyl group, a C.sub.1 -C.sub.4 lower alkoxy group, fluorine, chlorine, bromine and an amino group, a C.sub.1 -C.sub.5 alkylphenyl group, a phenyl group having one to three substituents selected from a group consisting of a C.sub.1 -C.sub.4 lower alkyl group, a C.sub.1 -C.sub.4 lower alkoxy group, fluorine, chlorine, bromine and an amino group, a substituted or unsubstituted guanidino group, or an amino group having a general formula: NR.sub.3 R.sub.4 in which R.sub.3 and R.sub.4, identical to or different from each other, represent independently a hydrogen atom, a C.sub.1 -C.sub.6 lower alkyl group, a C.sub.3 -C.sub.

Abstract: Novel 4-amino-3-acylnaphthyridine derivatives represented by formula (I), wherein R.sub.1 is hydrogen, C.sub.1 -C.sub.6 lower alkyl group, C.sub.1 -C.sub.6 lower alkoxy group, C.sub.1 -C.sub.6 lower alkoxyalkyl group, C.sub.3 -C.sub.6 cycloalkyl group, C.sub.3 -C.sub.6 cycloalkyl C.sub.1 -C.sub.6 alkyl group, a or phenyl group which maybe substituted with C.sub.1 -C.sub.6 alkyl group; R.sub.2 is hydrogen, C.sub.1 -C.sub.6 lower alkyl group, C.sub.1 -C.sub.6 alkoxy group, C.sub.1 -C.sub.6 alkylthio group, or a group of the formula: NR.sub.6 R.sub.7 wherein R.sub.6 and R.sub.7, identical to or different from each other, are independently hydrogen or C.sub.1 -C.sub.6 lower alkyl group, or R.sub.6 and R.sub.7 may form together 5-membered or 6-membered cycloalkyl group; R.sub.3 is hydrogen, C.sub.1 -C.sub.6 lower alkyl group, C.sub.1 -C.sub.6 alkoxy group, C.sub.1 -C.sub.6 alkylthio group, an amino group substituted with one or two C.sub.1 -C.sub.6 alkyl groups, halogen, cyano group, C.sub.1 -C.sub.