2-(4-chlorophenyl)-3-methyl-4-oxido-6-phenylpyrazin-1-ium 1-oxide 2-(4-chlorophenyl)-3-methyl-4-oxido-6-phenyl-pyrazin-1-ium 1-oxide MLS000775949 SMR000439936 ZINC02352164 3-(4-Chloro-phenyl)-2-methyl-5-phenyl-pyrazine 1,4-dioxide