2-Carbonylamino-6-piperidinaminopiridinas substituted 1-carbonylamino and 3-piperidinaminobencenos substituted-as agonists of 5-HT1F

Compound of formula I: or a salt pharmaceutically acceptable acid addition thereof, wherein; X is -C (R3c) = or -N =; R1 is phenyl, substituted phenyl, heterocycle or substituted heterocycle, wherein the heterocycle is selected from the group consisting of pyridinyl, thiophenyl and furanyl and wherein substituted phenyl means that the ring moiety is: i. substituted with one to three halogen substituents; or ii. substituted with one to two substituents independently selected from the group consisting of halogen, methyl, methoxy, trifluoromethyl, trifluoromethoxy and cyano; and wherein substituted heterocycle mean the ring moiety is mono-substituted by halogen; R2 is hydrogen; n-alkyl C1-C3, cycloalkyl-C3-C6-alkyl-C1-C3, or a group of formula II R 3a, R 3b, and when X is -C (R 3c) =, R 3c are each independently hydrogen, fluorine or methyl provided that no more than one of R3a, R3b and R3c may be other than hydrogen; R4 is hydrogen; and R5 is hydrogen or methyl, provided that when R3a is other than hydrogen, R5 is hydrogen; R6 is hydrogen or C1-C6 alkyl; n is an integer from 1 to 6 inclusive.