Synthesis of 1-beta-D-(5-deoxy-5-iodoarabinofuranosyl)-2-nitroimidazole (beta-IAZA): a novel marker of tissue hypoxia

The present work describes the synthesis of the beta-isomer of 1-alpha-D-(5-deoxy-5-iodoarabinofuranosyl)-2-nitroimidazole (IAZA). Radioiodinated IAZA ((123)I-IAZA) has been extensively studied as a radiopharmaceutical for the diagnosis of regional and/or focal tissue hypoxia in a variety of clinical pathologies. The beta-anomer of IAZA, 1-beta-D-(5-deoxy-5-iodoarabinofuranosyl)-2-nitroimidazole (beta-IAZA, 1), was synthesized via an unconventional route starting from 1-beta-D-(ribofuranosyl)-2-nitroimidazole (AZR), with a change of configuration at the C-2'-position to afford 1-beta-D-(arabinofuranosyl)-2-nitroimidazole (beta-AZA, 7). Nucleophilic iodination of the 5'-O-toluenesulfonyl-2',3'-di-O-acetyl precursor of beta-AZA, 9, followed by deprotection, afforded 1 in satisfactory yield. beta-IAZA (1) was also synthesized from 7 using molecular iodine and triphenylphosphine.     

The use of Nafion-H® as an efficient catalyst for the direct conversion of primary and secondary trimethylsilyl ethers to their corresponding ethers under mild and heterogeneous conditions

Primary and secondary trimethylsilyl ethers were converted to their corresponding ethers in the presence Nafion-H® with good to excellent yields under mild and heterogeneous conditions.     

Trichloroisocyanuric acid as a novel oxidizing agent for the oxidation of 1,3,5-trisubstituted pyrazolines under both heterogeneous and solvent free conditions

Trichloroisocyanuric acid is used as an effective oxidizing agent for the oxidation of 1,3,5-trisubstituted pyrazolines to their corresponding pyrazoles under both heterogeneous and also solvent free conditions with good yields at room temperature.     

4-(p-Chloro)phenyl-1,2,4-triazole-3,5-dione as a novel and reusable reagent for the oxidation of 1,3,5-trisubstituted pyrazolines under mild conditions

4-(p-Chloro)phenyl-1,3,4-triazole-3,5-dione is used as an effective oxidizing agent for the oxidation of 1,3,5-trisubstituted pyrazolines to their corresponding pyrazoles under mild conditions with moderate to good yields at room temperature.     

Sulfonic acid-functionalized Fe3O4-supported magnetized graphene oxide quantum dots: A novel organic-inorganic nanocomposite as an efficient and recyclable nanocatalyst for the synthesis of dihydropyrano[2,3-c]pyrazole and 4H-chromene derivatives

In this research, the main emphasis has been focused on the preparation of a novel Fe₃O₄-supported propane-1-sulfonic acid-grafted graphene oxide quantum dots (Fe₃O₄@GOQD-O-(propane-1-sulfonic acid)) that it was readily synthesized via a five-step procedure as a hitherto unreported magnetic nanocatalyst. This newly prepared Fe₃O₄@GOQD-O-(propane-1-sulfonic acid) nanocomposite was structurally well-established by different analytical techniques including Fourier transform infrared (FT-IR), X-ray diffraction (XRD), energy-dispersive X-ray (EDX), thermal gravimetric analysis (TGA), field emission gun-scanning electron microscope (FESEM), high-resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM) analyses. The high catalytic performance of this nanocomposite was exhibited in one-pot synthesis of dihydropyrano[2,3-c]pyrazole and 4H-chromene derivatives under mild conditions. Low reaction times, excellent yields of the products, benignity of the catalyst, easy reaction work-up and magnetic recyclability of the catalyst are the main advantages of the present protocol. Also, our research indicated that the Fe₃O₄@GOQD-O-(propane-1-sulfonic acid) could be reused up to five times without considerable loss of catalytic activity.     

Structural and spectroscopic properties of trans-difluoro(1,4,8,12-tetraazacyclopentadecane)chromium(III) perchlorate hydrate

The structure of [CrF(2)([15]aneN(4))]ClO(4).H(2)O ([15]aneN(4)=1,4,8,12-tetraazacyclopentadecane) has been determined by a single-crystal X-ray diffraction study at 173 K. The complex crystallizes in the space group P1- of the triclinic system with two mononuclear formula units in a cell of dimensions a=9.6117(7) A, b=10.2882(7) A, c=11.0001(7) A and alpha=99.7570(10) degrees, beta=105.6080(10) degrees and gamma=113.7130(10) degrees. The complex cation unit has its central Cr atom in an octahedral coordination with four nitrogen atoms and two fluorine atoms in a trans position. Three six-membered and one five-membered chelate rings of the [15]aneN(4) ligand are in a chair-twist(skew)-chair-gauche conformation sequence. The gauche five-membered ring is disordered with the twist six-membered ring opposite. The four H atoms in the chiral N atoms have the trans-II (CTCg) type configuration. The mean Cr-N and Cr-F bonds are 2.095(2) and 1.8752(13) A, respectively. The IR and visible spectral properties are consistent with the result of X-ray crystallography. The resolved band maxima of the electronic d-d spectrum are fitted with secular determinant for quartet state energy of d(3) configuration in tetragonal field including configurational but neglecting spin-orbit coupling. It is confirmed that the fluoride has strong sigma- and pi-donor properties toward the chromium(III) ion and the nitrogen atoms of the [15]aneN(4) ligand also have a strong sigma-donor character.     

Radiosynthesis and biological evaluation of 166Ho labeled methoxylated porphyrins as possible therapeutic agents

¹⁶⁶Ho labeled 5,10,15,20-tetrakis(3,4-dimethoxyphenyl) porphyrin, and 5,10,15,20-tetrakis(3,4,5-trimethoxyphenyl) porphyrin ([¹⁶⁶Ho]–TDMPP and [¹⁶⁶Ho]–TTMPP respectively) were prepared with acceptable radiochemical purity and specific activities. Stability and partition coefficient of the complexes were determined in the final formulations and biodistribution studies in mouse demonstrated high accumulation of [¹⁶⁶Ho]–TDMPP in the lung and liver and less excretion through the kidney. while [¹⁶⁶Ho]–TTMPP was mostly excreted into intestines and kidneys while lungs were a minor accumulation site. In contrast to other reported radiolanthanide labeled porphyrins these two complexes showed less liver accumulation. Further investigation of their potential therapeutic properties is of interest.     

An Efficient Method for the Synthesis of N-Acylsulfonamides: One-pot Sulfonylation and Acylation of Primary Arylamines under Solvent-Free Conditions

Summary. The preparation of N-acylsulfonamides is described using primary amines, arylsulfonyl chlorides and acyl chlorides. Reaction of primary aryl amines with arylsulfonyl chlorides in the presence of NaHCO₃ produced N-arylsulfonamides, which reacted in situ with benzoyl chloride furnishing the corresponding N-benzoyl-N-arylsulfonamides in 72–96% yields. Accordingly, 4-nitrobenzoyl chloride and 3,5-dinitrobenzoyl chloride were used as acylating agents. All the reactions were carried out under solvent-free conditions at room temperature and the products were isolated after simple work-up in high yields and purity.     

Computational modeling of porous medium inside a channel with homogeneous nanofluid

Journal of Thermal Analysis and Calorimetry - In the present study, the flow field and heat transfer have been simulated numerically inside a channel. The channel is under the constant heat flux....     

Heat transfer enhancement in a counter-flow sinusoidal parallel-plate heat exchanger partially filled with porous media using metal foam in the channels’ divergent sections

Journal of Thermal Analysis and Calorimetry - This is a numerical study of heat transfer and flow in a counter-flow sinusoidal parallel-plate heat exchanger using metal foam in the channels’...