A compound of Formula 1wherein R1 represents hydrogen, halo, a C1-C4 alkyl group, a C1-C4 alkylhalide group, a C1-C4 alkoxy-C2-C4 alkyl group, a C2-C4 alkenyl group, a C2-C4 alkynyl group or a C3-C7 cycloalkyl group；R2 representsor a tautomer thereof； andR3 represents hydrogen, a C1-C4 alkyl group, a C1-C4 alkoxy-C2-C4 alkyl group or a C3-C7 cycloalkyl group；or a pharmaceutically acceptable salt or solvate thereof.Processes to prepare said compounds and novel intermediates are also claimed. Such compound finds utility in treating neuropathic pain and disorders of the central nervous system.
