Thiazole compound and use thereof

An object of the present invention is to provide a novel thiazole compound with specific inhibitory activity against phosphodiesterase 4. The present invention provides a compound represented by Formula (1), an optical isomer thereof, or a salt thereof: wherein R1 is a di-C 1-6 alkoxyphenyl group; R2 is any one of the following groups (a) to (t): (a) a phenyl group; (b) a naphthyl group; (c) a pyridyl group; (d) a furyl group; (e) a thienyl group; (f) an isoxazolyl group; (g) a thiazolyl group; (h) a pyrrolyl group; (i) an imidazolyl group; (j) a tetrazolyl group; (k) a pyrazinyl group; (1) a thienothienyl group; (m) a benzothienyl group; (n) an indolyl group; (o) a benzimidazolyl group; (p) an indazolyl group; (q) a quinolyl group; (r) a 1,2,3,4-tetrahydroquinolyl group; (s) a quinoxalinyl group; and (t) a 1,3-benzodioxolyl group; and A is any one of the following groups (i) to (vi): (i) -CO-B- wherein B is a C 1-6 alkylene group; (ii) -CO-Ba wherein Ba is a C 2-6 alkenylene group; (iii) -CH(OH)-B-; (iv) -COCH(COOR3)-Bb- wherein R3 is a C 1-6 alkyl group and Bb is a C 1-6 alkylene group; and (v) -Bc- wherein Bc is a C 2-6 alkylene group.