Rapid Microwave Induced Palladium Catalyzed Amination of Aryl Bromides

Summary.  The palladium-catalyzed coupling reaction of aryl bromides with various amines under microwave irradiation was studied using PdCl₂ [P(o-tolyl)₃]₂ which gave various aryl amines in good yields. The reactions were carried out under normal atmospheric conditions. Received September 3, 2001. Accepted October 10, 2001     

Syntheses,crystal, molecular structures,and solution studies of Cu(II), Co(II), and Zn(II) coordination compounds containing pyridine-2,6-dicarboxylic acid and 1,4-pyrazine-2,3-dicarboxylic acid: comparative computational studies of Cu(II) and Zn(II) complexes

Structural Chemistry - Three new coordination compounds of Cu(II), Co(II), and Zn(II) based on different dicarboxylic acids formulated as (AcrH)[Cu(pydc)(pydcH)]·5H2O (1)...     

Depth dose evaluation for prostate cancer treatment using boron neutron capture therapy

Considering the advantages of boron neutron capture therapy (BNCT) in treating prostate cancer, the amount of dose delivered to tumour and healthy tissues must be determined. Therefore, in this study, Monte Carlo analyses were performed to evaluate physical doses of adjacent healthy tissues and prostate tumours located at different depths of reference phantom developed by International Commission on Radiological Protection. According to the results, when prostate depth decreases, the amount of physical dose in tumour increases but the physical doses of healthy organs around the tumour remain constant. As expected, lithium filter decreases the damages to normal tissues. The estimations of physical dose, dose uniformity and dose distribution suggested that using BNCT with a filtered neutron beam could be applicable for prostates locate at the depths less than 7 cm from the body surface, which occurs in 5 % of all subjects.     

Chemical shielding properties for BN,BP, AlN,and AlP nanocones: DFT studies

The properties of boron nitride (BN), boron phosphide (BP), aluminum nitride (AlN), and aluminum phosphide (AlP) nanocones were investigated by density functional theory (DFT) calculations. The investigated structures were optimized and chemical shielding (CS) properties including isotropic and anisotropic CS parameters were calculated for the atoms of the optimized structures. The magnitudes of CS parameters were observed to be mainly dependent on the bond lengths of considered atoms. The results indicated that the atoms could be divided into atomic layers due to the similarities of their CS properties for the atoms of each layer. The trend means that the atoms of each layer detect almost similar electronic environments. Moreover, the atoms at the apex and mouth of nanocones exhibit different properties with respect to the other atomic layers.     

An investigation of hydrogen-bonding effects on the nitrogen and hydrogen electric field gradient and chemical shielding tensors in the 9-methyladenine real crystalline structure: a density functional theory study

Hydrogen-bonding effects in the real crystalline structure of 9-methyladenine, 9-MA, were studied using calculated electric field gradient, EFG, and chemical shielding, CS, tensors for nitrogen and hydrogen nuclei via density functional theory. The calculations were carried out at the B3LYP and B3PW91 levels with the 6-311++G basis set via the Gaussian 98 package. Nuclear quadrupole coupling constants, C(Q), and asymmetry parameters, eta(Q), are reported for (14)N and (2)H. The chemical shielding anisotropy, Deltasigma, and chemical shielding isotropy, sigma(iso), are also reported for (15)N and (1)H. The difference between the calculated parameters of the monomer and heptameric layer-like cluster 9-MA shows how much H-bonding interactions affect the EFG and CS tensors of each nucleus. This result indicates that N(10) (imino nitrogen) has a major role in H-bonding interactions, whereas that of N(9) is negligible. There is good agreement between the present calculated parameters and reported experimental data. Although some discrepancies were observed, this could be attributed to the different conditions which were applied for calculation and the experiments.     

An unsymmetrical approach to the synthesis of bismethylene triphosphate analogues

A protected, unsymmetrical bismethylene triphosphate analogue was prepared by sequential Michaelis-Arbuzov reactions on ethyl bis(halomethyl)phosphinates. This species was monodeprotected at one of the terminal phosphonate groups in high yield. The resulting monodeprotected compound was used to achieve the first syntheses of the bismethylene triphosphate analogues of UTP and CTP.     

[Omim][BF4], a green and recyclable ionic liquid medium for the one-pot chemoselective synthesis of benzoxazinones

An efficient procedure for the one-pot chemoselective synthesis of 2H-benzo[b][1,4]oxazin-3(4H)-one derivatives from their corresponding o-aminophenols is developed using DBU in the ionic liquid [omim][BF₄]. Upon completion of the reaction and separation of the product, the ionic liquid is recovered and successfully reused over nine recycles without any noticeable loss of performance.