A convergent synthesis of adenosine A2a agonist 1 in the form of its maleate salt 2 was achieved. The key step in this approach was the highly selective 9beta-glycosylation reaction between 2-haloadenines or an N(2)-alkyl-6-chloroguanine and a D-ribose derivative containing a 2-ethyltetrazolyl moiety. Glycosylations of other purine derivatives were also examined, and the methods developed provide efficient access to a variety of adenosine analogues such as 2-alkylaminoadenosines, an attractive class of compounds with antiinflammatory activity. 相似文献
Reaction between the dichloroboryl complex, Os(BCl2)Cl(CO)(PPh3)2, and water replaces both chloride substituents on the boryl ligand, without cleavage of the Os---B bond, giving yellow Os[B(OH)2]Cl(CO)(PPh3)2 (1). Compound 1 can be regarded as an example of a ‘metalla–boronic acid’ (LnM---B(OH)2) and in the solid state, X-ray crystal structure determination reveals that molecules of 1 are tetragonal pyramidal in geometry (Os---B, 2.056(3) Å) and are arranged in pairs, as hydrogen-bonded dimers. This same arrangement is found in the crystalline state for simple boronic acids. Reaction between the dichloroboryl complex, Os(BCl2)Cl(CO)(PPh3)2, and methanol and ethanol produces yellow Os[B(OMe)2]Cl(CO)(PPh3)2 (2a) and yellow Os[B(OEt)2]Cl(CO)(PPh3)2 (2b), respectively. The crystal structure of 2b reveals a tetragonal pyramidal geometry with the diethoxyboryl ligand in the apical site and with an Os---B bond distance of 2.081(5) Å. Reaction between Os(BCl2)Cl(CO)(PPh3)2, and N,N′-dimethyl-o-phenylenediamine and N,N′-dimethyl-ethylenediamine produces yellow
Full-size image
(5) and yellow
Full-size image
(6), respectively. Compounds 1, 2a, 2b, 5, and 6 all react with carbon monoxide to give the colourless, six-coordinate complexes Os[B(OH)2]Cl(CO)2(PPh3)2 (3), Os[B(OMe)2]Cl(CO)2(PPh3)2 (4a), Os[B(OEt)2]Cl(CO)2(PPh3)2 (4b),
Full-size image
(7), and
Full-size image
(8), respectively, but in the case of 6 only, this CO uptake is easily reversible. The crystal structure of 5 is also reported. 相似文献
The iridium(I) complex [Ir(CO2Me)(CO)2(PPh3)2] undergoes a transesterification reaction with the alcohols CH2C(R)CH2OH (R = H, Me), MeCCCH2CH2OH, and HOCH2CH2OH to afford the complexes [Ir(CO2CH2CH2CMe)(CO)2(PPh3)2] and [Ir(CO2CH2CH2OH)(CO)2(PPh3)2], respectively. In contrast the acetylenic alcohol HCCCH2CH2OH gives [Ir(CCCH2CH2OH)(CO)PPh3)2]. Some reactions of the new complexes are described. 相似文献
[OS(η2-CS2Me)(CO)2(PPH3)2]+ and [Ir(η2-CS2Me)Cl(CO)(PPh3)2)+ react with NaBH4 giving OsH(CS2Me)(CO)2(PPh3)2 and IrH(CS2Me)Cl(CO)(PPh3)2 respectively; These compounds contain mutually hydride and η1-dithiomethylester ligands and upon heating undergo 1,2-elimination of MeSH producing Os(CS)(CO)2(PPh3)2 and IrCl(CS)(PPh3)2. 相似文献
A high-yield synthesis of trans-RuCl2(CS)(H2O)(PPh3)2 from RuCl2(PPh3)3 and CS2 is described. The coordinated water molecule is labile, and introduction of CNR (R p-toyl or p-chlorophenyl) leads to yellow trans-RuCl2(CS)(CNR)(PPh3)2, which isomerises thermally to colourless cis-RuCl2(CS)(CNR)(PPh3)2. Reaction of AgClO4 with cis-RuCl2(CS)(CNR)(PPh3)2 gives [RuCl(CS)(CNR)(H2O)(PPh3)2]+, from which [RuCl(CS)(CO)(CNR)(PPh3)2]+ and [RuCl(CS)(CNR)2(PPh3)2]+ are derived. Reaction of trans-RuCl2(CS)(H2O)(PPh3)2 with sodium formate gives Ru(η2-O2CH)Cl(CS)(PPh3)2, which undergoes decarboxylation in the presence of (PPh3) to give RuHCl(CS)(PPh3)3. Ru(η2-O2CH)H(CS)(PPh3)2 and Ru(η2-O2CMe)-H(CS)(PPh3)2 are also described. 相似文献
An energy-dependent phase-shift analysis of 0–21 MeV n-α scattering is presented and compared to the previous 0–23 MeV p-α analysis. The error matrix and inverse error matrix for both the n-α and the p-α analyses are given. 相似文献
Free fatty acid (FFA) compositions are examined in feedstock for biodiesel production, as source-specific markers in soil, and because of their role in cellular signaling. However, sample preparation of FFAs for gas chromatography-mass spectrometry (GC-MS) analysis can be time and labor intensive. Therefore, to increase sample preparation throughput, a glass microfluidic device was developed to automate derivatization of FFAs to fatty acid methyl esters (FAMEs). FFAs were delivered to one input of the device and methanolic-HCl was delivered to a second input. FAME products were produced as the reagents traversed a 29 μL reaction channel held at 55 °C. A Design of Experiment protocol was used to determine the combination of derivatization time (T(der)) and ratio of methanolic-HCl:FFA (R(der)) that maximized the derivatization efficiencies of tridecanoic acid and stearic acid to their methyl ester forms. The combination of T(der) = 0.8 min and R(der) = 4.9 that produced optimal derivatization conditions for both FFAs within a 5 min total sample preparation time was determined. This combination of T(der) and R(der) was used to derivatize 12 FFAs with a range of derivatization efficiencies from 18% to 93% with efficiencies of 61% for tridecanoic acid and 84% for stearic acid. As compared to a conventional macroscale derivatization of FFA to FAME, the microfluidic device decreased the volume of methanolic-HCl and FFA by 20- and 1300-fold, respectively. The developed microfluidic device can be used for automated preparation of FAMEs to analyze the FFA compositions of volume-limited samples. 相似文献
