article chemical structure unclassified drug acetylation proton nuclear magnetic resonance thiosemicarbazone derivative carbon nuclear magnetic resonance heterocyclic compound priority journal reaction analysis structure analysis synthesis Acetylation Thiosemicarbazones chemical reaction cyclization mass spectrometry oxadiazole derivative tetrazole derivative 1,2,3,4 di o isopropylidene beta levo arabinopyranos 5 yl 1,3,3 trimethyl 2 norcamphanone 1,3,4 oxadiazole derivative 2 phenyl 5 glycosyl 1,3,4 oxadiazole 3,4 dihydronaphthalen 1(2h) one thiosemicarbazone 3,4' dimethoxybenzophenone thiocarbamazone 4 methoxybenzophenone thiocarbamazone 4,4' dimethoxybenzophenone thiocarbamazone 5 [5' (1',2':3',4' di o isopropylidene beta levo arabinopyranosyl]tetrazole 5 acetamido 3 n acetyl 2 (3',4' dimethoxyphenyl) 2 phenyl 1,3,4 thiadiazoline 5 acetamido 3 n acetyl 2 (4' methoxyphenyl) 2 phenyl 1,3,4 thiadiazoline