Disclosed are a compound of Formula I,having higher inhibition of protein kinase G (PKG) activity and pharmaceutically acceptable salts thereof. In Formula I, R1 and R2 are the same or different, each being independently chosen from the halogens, the C1-C6 alkoxyl group, the C1-C6 alkyl group, the C2-C6 alkenyl group, and the C2-C6 alkynyl group R3 is chosen from H, the halogens, the substituted or unsubstituted C1-C6 alkyl group, C3-C6 cycloalkyl group, C2-C6 alkenyl group, and C2-C6 alkynyl group, aryl group, and heteroaryl group and n is an integer between 0 and 15. Also disclosed is a pharmaceutical composition comprising said compound, the use of the compound in treating pains, in particular chronic pain, a preparation method for the compound, and a new intermediate.
