drug analysis drug identification 4 drug synthesis 4 infrared spectrometry mass spectrometry 4 theoretical study 4 radioisotope 3 Synthesis 2 in vitro study 2 nonhuman 2 nuclear magnetic resonance 2 preliminary communication 2 thin layer chromatography 2 20 hydroxy 3 oxo 23 norchol 4 enoic acid c 14 1 3 oxo 23 norchola 4,20(22) dienoic acid c 14 1 3beta acetoxy 5beta pregnan 20 one 1 3beta hydroxy 23 norchol 20(22) enoic acid c 14 1 3beta hydroxy 23 norchola 5,20(22) dienoic acid c 14 1 3beta,20 dihydroxy 23 norchol 5 enoic acid c 14 1 3beta,20 dihydroxy 23 norcholanic acid c 14 1 5beta pregnan 3beta ol 20 one c 14 1 Ethyl |1‐14C| bromoacetate 1 Hordenine‐α‐14C 1 Reformatsky reaction 1 Tyramine‐α‐14C 1 drug structure 1 hordenine c 14 1 methodology 1 priority journal 1 proton nuclear magnetic resonance 1