Synthesis of 6-Amino-4-aryl-5-cyano-3- (3-cyanopyridin-2-ylthiomethyl)-2,4-dihydropyrano[2,3-c]pyrazoles and Their Hydrogenated Analogues. Molecular Structure of 6-Amino-5-cyano-3-(3-cyano-4,6-dimethylpyridin-2-ylthiomethyl)-4- (2-nitrophenyl)-2,4-dihydropyrano[2,3-c]pyrazole.