2,4-Dichloro-5-nitrophenol is an intermediate used to prepare (5-Substituted-pyrrolidinyl-2-carbonyl)-2-cyanopyrrolidines as Potent Dipeptidyl Peptidase IV Inhibitors. It is also used to synthesize cyanopyrrolo[2,3-d]pyrimidine derivatives as Hsp90 inhibitors.