A novel solid support for the synthesis of 3-aminoalkylated oligonucleotides

A novel improved controlled pore glass (CPG) support based on the 2-(hydroxymethyl)-6-nitrobenzoyl (HMNB) protecting group was developed for the synthesis of 3^′-aminoalkylated oligonucleotides. The release of oligonucleotides with free 3^′-amino groups from the support is complete within 2 h at 55 °C in concentrated ammonia.     

An extended ab initio QM/MM MD approach to structure and dynamics of Zn(II) in aqueous solution

Structural and dynamical properties of Zn(II) in aqueous solution were investigated, based on an ab initio quantum mechanical/molecular mechanical (QM/MM) molecular dynamics simulation at double-zeta Hartree-Fock quantum mechanical level including the first and second hydration shells into the QM region. The inclusion of the second shell in the QM region resulted in significant changes in the properties of the hydrate. The first shell coordination number was found to be 6, the second shell consists of approximately 14 water molecules. The structural properties were determined in terms of RDF, ADF, tilt and theta angle distributions, while dynamics were characterized by mean ligand residence times, ion-ligand stretching frequencies and the vibrational and librational motions of water ligands.     

Novel Stereoselective Phase Transfer Catalytic Synthesis and Some Applications of ( E )-2-Chlorovinylthioarenes and Hetarenes

A novel two-step method for the preparation of ( E )-2-chlorovinylthioarenes (or hetarenes) from thiols and 1,1,2-trichloroethane in the phase transfer catalytic systems solid K 2 CO 3 /solid KI/18-crown-6/xylene and solid KOH/18-crown-6/toluene has been developed. ( E )-2-chlorovinylthioarenes were isolated in yields up to 98%. Utilization of ( E )-2-chlorovinylthioarenes in the Heck and Stille reactions has been shown.     

Hydrosilylation of Pyridinealdehydes and Acetylpyridines Catalyzed by Caesium Fluoride in the Presence of 18-Crown-6

Reactions of isomeric pyridinealdehydes and acetylpyridines with dime thylphenylsi lane proceed readily in dichloromethane in the presence of catalytic amounts of CsF and 18-crown-6 to give silyl ethers of the corresponding pyridyl carbinols in good yields (50–70%).     

Synthesis and Characterization of Novel Biodegradable Di‐ and Tri‐Block Copolymers Based on Ethylene Carbonate Polymer as Hydrophobic Segment

Synthesis of novel amphiphilic biodegradable block copolymers based on ethylene carbonate is reported in this study. Polyethylene glycol monomethyl ether (MeO‐PEO) and polyethylene glycol (PEG) of varying molar masses are used as macro‐initiator for ring‐opening polymerization of ethylene carbonate in the presence of sodium stannate trihydrate as a heterogeneous transesterification catalyst. Earlier elution of block copolymer from macro‐initiator in size exclusion chromatography (SEC) indicated the successful synthesis of the block copolymers. Ratios of both types of blocks are varied systematically. Liquid chromatography at critical conditions is used for the analysis of the non‐critical individual blocks, and if there are any critical segments that are not attached to the non‐critical block. To the best of our knowledge, this is the first report on the synthesis of ethylene carbonate‐based amphiphilic block copolymers. Chromatographic critical conditions of the ethylene carbonate polymer are also reported for the first time. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1887–1893     

Synthesis of Isopropyl and Tert-butyl Pyridyl Ketones by Alkylation of Acetylpyridines with Methyl Iodide Using Phase Transfer Catalysis

Isomeric acetylpyridines undergo regiospecific alkylation with methyl iodide under solid/liquid phase transfer conditions (aromatic solvent/KOH/18-crown-6) to give the corresponding isopropyl and/or tert-butyl pyridyl ketones, depending on reaction conditions.     

Transition metal-catalyzed hydro-, sila-, and stannastannation of cyclopropenes: stereo- and regioselective approach toward multisubstituted cyclopropyl synthons

The first highly efficient, stereo- and regioselective palladium-catalyzed hydro-, sila-, and stannastannation of cyclopropenes to give multisubstituted cyclopropylstannanes have been developed. It was shown that the addition across the double bond of cyclopropene is generally controlled by steric factors and proceeds from the least hindered face. The directing effect of alkoxymethyl substituents in the hydrostannation reaction of 3,3-disubstituted cyclopropenes was demonstrated. This methodology represents a powerful and atom-economic approach toward a wide variety of highly substituted cyclopropylstannanes, important building blocks unavailable by other methods.     

Synthesis, biodistribution and evaluation of 99mTc-sitafloxacin kit: a novel infection imaging agent

Radiosynthesis of ^99mTc-sitafloxacin (^99mTc-STF) complex and its efficacy as a potential infection imaging agent was evaluated. Effect of sitafloxacin (STF) concentration, sodium pertechnetate (Na^99mTcO₄), stannous chloride dihydrate (SnCl₂·2H₂O), and pH on the % radiochemical purity yield (RCP) of ^99mTc-STF complex was studied. A stable ^99mTc-STF complex up to 120 min with maximum %RCP yield was observed by mixing 2 mg of STF with 3 mCi of Na^99mTcO₄ and 150 μL of SnCl₂·2H₂O (1 μg/μL in 0.01 N HCl) at a pH 5.5. Artificially infected rats with Staphylococcus aureus were used for studying the biodistribution behavior of the ^99mTc-STF complex. After 30 min of the intravenous (I.V.) administration of the ^99mTc-STF complex, 7.50 ± 0.10% was absorbed in the infected thigh of the rats and the uptake gradually increased to 18.50 ± 0.20% within 90 min. Rabbits with artificially induced infection were used for evaluating the scintigraphic accuracy. Higher uptake in the infected thigh was observed after 2 h of I.V. administration of the ^99mTc-STF complex. Target to non-target organ ratio of the % absorbed dose incase of infected/normal muscle was 6.82 ± 0.40, 17.11 ± 0.60, and 23.13 ± 1.00% at 30, 60 and 90 min of administration. Stable and higher %RCP, higher uptake in the infected thigh, and spectral studies, recommend the ^99mTc-STF for routine infection imaging.