4-Chloro-8-(methylthio)isothiazolo[4',3':4,5]thieno[3,2-d][1,2,3]triazine 4-Chloroisothiazolo[4',3':4,5]thieno[3,2-d][1,2,3]triazin-8-yl methyl sulfide AIDS-133511 AIDS133511 NSC629414