Complexes of orotic acid and derivatives with the fac-[M(CO)3]+ (M = Re and 99Tc/99mTc) core as radiopharmaceutical probes

We report the aqueous synthesis of complexes of orotic acid (H2oa) and derivatives (5-fluoroorotic acid (H2foa) and 5-aminoorotic acid (H2aoa)) with the organometallic fac-[M(CO)3]+ (M = Re and 99Tc/99mTc) moiety. Complexes [Re(CO)3(OH2)(oa)]- (1) and [99mTc(CO)3(OH2)(oa)]- (2) were obtained with H2oa in water from [Re(CO)5Br] and [99mTc(CO)3(OH2)3]+ respectively. Complexes [M(CO)3(OH2)(foa)]- (M = Re (3), 99mTc (4)) were obtained as for the synthesis of 1 and 2. The structural identities of complexes 1–4 were confirmed by coinjection in the HPLC by UV/Vis detection coupled with a γ-detector. Complex [99Tc(CO)3(OH2)(foa)]- (5) was obtained from [99TcCl3(CO)3]2- and H2foa in water. The structures of 3 and 5 were elucidated by single crystal X-ray crystallography. Coinjection of 4 and 5 assessed the identity of the respective 99mTc complex. The reaction of 5-aminoorotic acid (H2aoa) with [Re(CO)5Br] in water resulted in the ligand-bridged dimeric complex [(Re(µ-aoa)(CO)3]22– (6). The reaction of H2aoa with [99mTc(CO)3(OH2)3]+ in water led to the monomeric 99mTc complex only

Thiocyanate-induced N-activation and nucleophilic 1,2-dearomatization of pyridinedicarbonyl dichloride: a synthetic route to a novel 1,2-dihydropyridine-based heterocyclic compound

The 1,2-dearomatized pyridine derivatives are among the most beneficial scaffolds for synthetic and medicinal chemistry and have along with others substantially contributed to pharmaceutical research. We report uncatalyzed thiocyanate-induced N-activation and nucleophilic 1,2-dearomatization of pyridinedicarbonyl dichloride with further addition of diphenylamine leading to the novel 1,2-dihydropyridine-based heterocyclic compound; ( +/-) 2 '-(diphenylamino)-3-thioxo-2,3-dihydro-1H,4 ' H-spiro[imidazo[1,5-a]pyridine-5,5 '-thiazole]-1,4 '-dione (1). The previously reported dearomatizations of pyridine and its derivatives usually demand a specific catalyst. Therefore, uncatalyzed 1,2-dearomatization of pyridinedicarbonyl dichloride observed in this study is unusual. Heterocyclic compound 1 will act as potential mother reagent for the synthetic route to a variety of novel heterocyclic compounds derivative to 1,2-dihydropyridine. The purity of the product was assessed by Ultraperformance Liquid Chromatography (UPLC), and the structural characterization was achieved by H-1 NMR, C-13 NMR, DEPT-135-NMR, IR, Liquid Chromatography Mass Spectrometry (ESI-MS), single crystal X-ray crystallography and density function theory (DFT)

New Flavonol Glucuronides from the Flower Buds of <i>Syzygium aromaticum</i> (Clove)

Repeated chromatography of the EtOAc-soluble fraction from the 70% EtOH extract of the flower buds of <i>Syzygium aromaticum</i> (clove) led to the isolation and characterization of four new flavonol glucuronides, rhamnetin-3-<i>O</i>-β-d-glucuronide (<b>1</b>), rhamnazin-3-<i>O</i>-β-d-glucuronide (<b>2</b>), rhamnazin-3-<i>O</i>-β-d-glucuronide-6″-methyl ester (<b>3</b>), and rhamnocitrin-3-<i>O</i>-β-d-glucuronide-6″-methyl ester (<b>4</b>), together with 15 flavonoids (<b>5</b>–<b>19</b>) having previously known chemical structures. The structures of the new compounds <b>1</b>–<b>4</b> were determined by interpretation of spectroscopic data, particularly by 1D- and 2D-NMR studies. Six flavonoids (<b>6</b>, <b>7</b>, <b>9</b>, <b>14</b>, <b>18</b>, and <b>19</b>) were isolated from the flower buds of <i>S. aromaticum</i> for the first time in this study. The flavonoids were examined for their cytotoxicity against human ovarian cancer cells (A2780) using MTT assays. Among the isolates, pachypodol (<b>19</b>) showed the most potent cytotoxicity on A2780 cells with an IC₅₀ value of 8.02 μM