2-(4-Methoxyphenyl)-1-methylene-3-phenyl-1,2-dihydropyrazino[1,2-a]benzimidazole AIDS-150390 AIDS150390 Methyl 4-(1-methylene-3-phenylpyrazino[1,2-a]benzimidazol-2(1H)-yl)phenyl ether NSC687521