Amino-heteroaryl derivatives as HCN blockers

The invention relates to amino-heteroaryl derivs. of formula I or a pharmaceutically acceptable salt for the treatment of pain, such as neuropathic pain or inflammatory pain. Compds. I, wherein Ar is Ph or a 6-membered heteroaryl group contg. 1 or 2 nitrogen atoms; X is O, S or alkylamino; R2 and R3 are independent C1-4 alkyl; C1-4 halo-substituted alkyl; (C1-4)alkyloxy(C1-4)alkyl, etc.; Y1, Y2 and Y3 are independent CH or N with the proviso that at least one of them is N and that when Y3 is N, Y is N; R4 and R5 are independent H, C1-4 alyl, halo-substituted C1-4 alkyl, etc.; their pharmaceutically acceptable salts are claimed. Compd. II was prepd. by cyclocondensation of 1-(dimethylamino)-4,4-dimethoxypent-1-en-3-one and guanidine hydrochloride; the resulting 4-(1,1-dimethoxyethyl)pyrimidin-2-amine underwent hydrolysis; the resulting 1-(2-aminopyrimidin-4-yl)ethanone underwent asym. redn.; the resulting (S)-1-(2-aminopyrimidin-4-yl)ethanol underwent reaction with 3-fluorophenol to give II. [on SciFinder(R)]