FIELD: chemistry.SUBSTANCE: invention relates to 2-aminopyridine derivatives of Formula (I) and Formula (III) (I) (III), where A1 is selected from the group consisting of a hydrogen atom and -O-(CHR1)-A4； R1 is selected unsubstituted methyl and methyl having 1–3 halogen atoms as substituents； A4 is phenyl optionally having one or more R4 as substituents； R4 is selected from the group consisting of a halogen atom, an unsubstituted C1-6 alkyl and C1-6 alkyl substituted with halogen atom (s)； A2 is selected from the group consisting of phenyl, pyridinyl and pyrimidinyl, optionally substituted with one or more substituents selected from halo and -OC1-6 alkyl, in which each hydrogen atom C1-6 alkyl moiety is optionally substituted with hydroxy or heteroalicyclic； A5 is a heteroalicyclyl which optionally has one or more substituents selected from the group consisting of =O, unsubstituted C1-6 alkyl, heteroalicyclyl, wherein heteroalicyclyl is optionally further substituted with a substituent(s) selected from the group consisting of C1-6 alkyl, =O, -OH, -COOH, -CN, a halogen atom, -NH(C1-6 alkyl) and -N(C1-6 alkyl)2, and C1-6 alkyl substituted with heteroalicyclic； A3 is selected from the group consisting of a hydrogen atom, a heteroaryl having as a substituent a phenyl, and heteroaryl ethynyl having as a substituent heteroarylalkyl, wherein each phenyl and heteroaryl optionally have one or more substituents selected from the group consisting of a halogen atom, C1-6 alkyl optionally having a halogen atom as substituents； provided that A1 and A3 At the same time they are not hydrogen atoms and one of A1 and A3 must be a hydrogen atom； and when A1 is -O-(CHR1)-A4 and R1 is methyl, A2 has, as substituents, at least one -OC1-6 alkyl, where C1-6 the alkyl moiety is optionally substituted with hydrogen or heteroalicyclic； and pharmaceutically acceptable salts thereof having an inhibitory activity against protein kinase.EFFECT: substituted 2-aminopyridine protein kinase inhibit
