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Abstract

Thiazolidinedione-containing compounds are a relatively recent class of oral hypoglycemic agents used today to treat type II diabetes mellitus. Vanadium is well known to be an effective agent for lowering blood-glucose levels. In this study, synthesis of the ligand precursors 5-[4-(3-hydroxypropoxy)benzyl]-2,4- thiazolidinedione (HPBT), 5-[4-(3-bromopropoxy)benzyl]-2,4-thiazolidinedione (BPBT), and 5-[4-(3-iodopropoxy)benzyl]-2,4-thiazolidinedione (IPBT) were accomplished at high purity in gram scale quantities. These were fully characterized by the methods mentioned below. Several synthetic pathways were examined, with varying success; 5-[4-(3-ptoluenesulfonylpropoxy) benzyl]-2,4-thiazolidinedione (TsPBT), N-BOC-5-[4-(3- hydroxypropoxy)benzyl]-2,4-thiazolidinedione (BocHPBT), N-BOC-5-[4-(3- iodopropoxy)benzyl]-2,4-thiazolidinedione (BocIPBT), and 5-[4-(3- sulfonylimidazolepropoxy)benzyl]-2,4-thiazolidinedione (ImPBT) were compounds on those pathways. 5-[4-(3-Acetyl-6-hexoxy-2-one)benzyl]-2,4-thiazolidinedione (APBT), was synthesized, but not successfully purified. The vanadium coordination complex, bis-(5-[4-(3-acetyl-6-hexoxy-2-one)benzyl]-2,4-thiazolidinedionato) oxovanadium VO(APBT)2) gave encouraging preliminary results, e.g., synthesis of the complex directly from IPBT and vanadyl acetylacetonate; however further purification of the ligand would be required to determine stability constants. The ligand precursors were characterized by ¹H NMR spectroscopy, mass spectrometry, elemental analyses, infrared spectroscopy and, in certain instances, ¹³C NMR spectroscopy and two dimensional NMR spectroscopy for HPBT and IPBT. BocHPBT was characterized as a pure compound with ¹H NMR spectroscopy. TsPBT, BocIPBT and ImPBT were not purified enough for complete characterization. LSIMS characterization of the thiazolidinedione oxovanadium(IV) complex, VO(APBT)₂, indicated that the synthetic pathway so far elucidated could ultimately be refined to yield this compound in greater purity and quantity.