4-(Hydroxyamino)-4-oxobutanoic acid CYANOACETIC ACID-OSU N-Hydroxysuccinimide Tofacitinib Impurity 2 Ethyl S-4-chloro-3-hydroxybutyrate 2-amino-4-fluoro-5-nitrobenzoic acid TF-A (3R,4R)-N,4-dimethyl-piperidin-3-amine (3R,4R)-3-[(6-amino-4-pyrimidinyl)methylamino]-4-methyl-β-oxo-1-Piperidinepropanenitrile (S)-N4-(3-chloro-4-fluorophenyl)-7-(tetrahydrofuran-3-yloxy)quinazoline-4,6-diaMine Tofacitinib Impurity 20 R-afatinib 6,7-Dihydro-N-methyl-N-[(3R,4R)-4-methyl-3-piperidinyl]-5H-pyrrolo[2,3-d]pyrimidin-4-amine 3-((3R,4R)-4-Methyl-3-(Methyl(7H-pyrrolo[2,3-d]pyriMidin-4-yl)aMino)piperidin-1-yl)-3-oxopropanaMide 3-((3S,4S)-4-methyl-3-(methyl(7H-pyrrolo[2,3-d]pyrimidin-4-yl)amino)piperidin-1-yl)-3-oxopropanenitrile 3-((3R,4R)-3-((2-chloro-7H-pyrrolo[2,3-d]pyriMidin-4-yl)(Methyl)aMino)-4-Methylpiperidin-1-yl)-3-oxopropanenitrile N-((3R,4S)-1-benzyl-4-methylpiperidin-3-yl)-N-methyl-7H-pyrrolo[2,3-d]pyrimidin-4-amine (3S,4S)-1-benzyl-N,4-diMethylpiperidin-3-aMine