- A N-Phosphinoamidinato NHC-Diborene Catalyst for Hydroboration
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The use of the N-phosphinoamidinato NHC-diborene catalyst 2 for hydroboration is described. The N-phosphinoamidine tBu2PN(H)C(Ph)= N(2,6-iPr2C6H3) was reacted with nBuLi in Et2O to afford the lithium derivative, which was then treated with B2Br4(SMe2)2 in toluene to form the N-phosphinoamidinate-bridged diborane 1. It was reacted with the N-heterocyclic carbene IMe (:C{N(CH3)C(CH3)}2) and excess potassium graphite at room temperature in toluene to give the N-phosphinoamidinato NHC-diborene compound 2. It can stoichiometrically activate ammonia-borane and carbon dioxide. It also showed catalytic capability. A 2 mol % portion of 2 catalyzed the hydroboration of carbon dioxide (CO2) with pinacolborane (HBpin) in deuterated benzene (C6D6) at 110 °C (conversion >99%), which afforded the methoxyborane [pinBOMe] (yield 97.8%, TOF 33.3 h-1) and the bis(boryl) oxide [(pinB)2O]. In addition, 5 mol % of 2 catalyzed the N-formylation of secondary and primary amines by carbon dioxide and pinacolborane to yield the N-formamides (average yield 91.6%, TOF 25.9 h-1). Moreover, 2 showed chemoselectivity toward catalytic hydroboration of carbonyl compounds. In mechanistic studies, the B= B double bond in compound 2 activated the substrates, the intermediates of which then underwent hydroboration with pinacolborane to yield the products and regenerate catalyst 2.
- Fan, Jun,Mah, Jian-Qiang,Yang, Ming-Chung,Su, Ming-Der,So, Cheuk-Wai
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p. 4993 - 5002
(2021/02/01)
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- Preparation and biodistribution of novel 99mTc(CO) 3-CNR complexes for myocardial imaging
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We evaluated lipophilicity and biodistribution of a series of 99mTc(CO)3-ether isonitrile complexes to determine whether different lipophilicity and structure of isonitrile ligands would improve the imaging properties of the radiopharmaceutical for the heart. Novel 99mTc(CO)3-MIBI analogs were prepared and analyzed by radio-HPLC, and their lipophilicity was determined. These new complexes could be bi- or tri-substituted in specified pH conditions like 99mTc(CO) 3-MIBI. These new complexes exhibited low liver, lungs and blood uptake compared with [99mTc(CO)3(MIBI)3] + though their heart uptake was not so high. Among these complexes, [99mTc(CO)3(EPI)2(OH2)]+ showed higher target to non-target ratios at 5 and 30 min post-injection than that of [99mTc(CO)3(MIBI)3]+. Copyright
- Hao, Guiyang,Zang, Jianying,Liu, Boli
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- Formylation with supercritical carbon dioxide over Ru/Al2O 3 modified by phosphines: Heterogeneous or homogeneous catalysis?
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The formylation of 3-methoxypropylamine with hydrogen and supercritical carbon dioxide over Ru-based catalysts was studied. In this solventless process, carbon dioxide acts as both reactant and solvent. Interestingly, Ru/Al2O3 modified by the phosphine 1,2-bis(diphenylphosphino)ethane (dppe) showed a high formylation activity at 100% selectivity, comparable to those of the homogeneous catalysts RuCl 2(dppe)2 and RuCl2(PPh3) 3. Analysis of the reaction mixture by ICP-OES and structural studies by in situ X-ray absorption spectroscopy discovered that the presence of the phosphine modifier led to the formation of a homogeneous ruthenium catalyst.
- Rohr, Markus,Grunwaldt, Jan-Dierk,Baiker, Alfons
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p. 144 - 153
(2007/10/03)
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- Process for the preparation of formamide compounds
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This invention relates to preparing formamide compounds in a process which comprises reacting an amine with a formylalkanolamine in the presence of carbon monoxide in which the mole ratio of amine to formylalkanolamine ranges from 0.2:1 to 5:1. The reaction is conducted at a temperature ranging from about 50° to 300° C. and a pressure ranging from about 100 to 10,000 psig. The amine employed in the reaction has the formula: STR1 wherein R' is hydrogen, an alkyl group of 1 to 10 carbon atoms, cyclohexyl, or --R"--O--R'", wherein R" is a divalent alkylene group of 2 to 4 carbon atoms and R'" is an alkyl group of 1 to 3 carbon atoms; and R is hydrogen or an alkyl group of 1 to 10 carbon atoms. The formylalkanolamine employed in the reaction has the formula: STR2 wherein R is an alkylene group of 1 to 3 carbon atoms, z is 0 or 1 and y is 1 or 2 and the sum of y and z is 2.
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- Long-range anisotropic effects of long chain amides
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In 1H-NMR spectra of amids with long-chain aliphatic N-substituents one observes - despite of the free mobility of the aliphatic chain - splitting of the signals of the terminal methyl groups which is caused by the hindered rotation of the amide bond. - Keywords: Amides; Hindered rotation; 1H-NMR
- Budzikiewicz, Herbert,Vieth, Peter-Eric,Krueger, Uwe
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p. 825 - 840
(2007/10/02)
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