65-64-5Relevant academic research and scientific papers
Extending the Scope of the B(C6F5)3-Catalyzed C=N Bond Reduction: Hydrogenation of Oxime Ethers and Hydrazones
Mohr, Jens,Porwal, Digvijay,Chatterjee, Indranil,Oestreich, Martin
, p. 17583 - 17586 (2015/12/05)
The B(C6F5)3-catalyzed hydrogenation is applied to aldoxime triisopropylsilyl ethers and hydrazones bearing an easily removable phthaloyl protective group. The C=N reduction of aldehyde-derived substrates (oxime ethers and hydrazones) is enabled by using 1,4-dioxane as the solvent known to participate as the Lewis-basic component in FLP-type heterolytic dihydrogen splitting. More basic ketone-derived hydrazones act as Lewis bases themselves in the FLP-type dihydrogen activation and are therefore successfully hydrogenated in nondonating toluene. The difference in reactivity between aldehyde- and ketone-derived substrates is also reflected in the required catalyst loading and dihydrogen pressure.
Convenient method for reduction of C-N double bonds in oximes, imines, and hydrazones using sodium Borohydride-Raney ni system
Yang, Yihua,Liu, Shouxin,Li, Junzhang,Tian, Xia,Zhen, Xiaoli,Han, Jianrong
experimental part, p. 2540 - 2554 (2012/07/27)
(Chemical Equation Presented) A practical method has been developed for reduction of C-N double bond in oximes, imines, and hydrazones with sodium borohydride catalyzed by Raney Ni. The reactions were carried out in basic aqueous solution, and the desired products were obtained in moderate yields after a simple procedure. This method can be applied to synthesize simpler aliphatic or aromatic amines and its analogs. Copyright Taylor & Francis Group, LLC.
ADENOSINE A2A RECEPTOR ANTAGONISTS
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Page/Page column 9, (2008/12/04)
Compounds having the structural formula I or a pharmaceutically acceptable salt thereof, wherein: X1 and X2 are 1-3 substituents independently selected from the group consisting of H, alkyl, halo, —CF3, —OCF3, alkoxy, —OH and —CN;n is 0, 1 or 2; andR and R1 are H or alkyl; also disclosed is the use of the compounds in the treatment of CNS diseases such as Parkinson's disease, alone or in combination with other agents for treating CNS diseases, pharmaceutical compositions comprising them and kits comprising the components of the combinations.
Tetrahydro-indazole cannabinoid modulators
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Page/Page column 100-102, (2008/06/13)
This invention is directed to a tetrahydro-indazole cannabinoid modulator compound of formula I: and a method for use in treating, ameliorating or preventing a cannabinoid receptor mediated syndrome, disorder or disease.
Limitations in the synthesis of high molecular weight polymers via nitroxide-mediated controlled radical polymerization: Experimental studies
Gray, Maisha K.,Zhou, Hongying,Nguyen, SonBinh T.,Torkelson, John M.
, p. 5792 - 5797 (2007/10/03)
Limitations associated with preparing high molecular weight polystyrene (PS) by nitroxide-mediated controlled radical polymerization have been tested by considering the role of unimolecular initiator concentration on active polymer radical concentration and thus degree of polymerization. Recent theories ignoring autopolymerization effects lead to the conclusion that, at low monomer conversion, the number-average molecular weight, Mn, scales with the -2/3 power of unimolecular initiator concentration. Bulk polymerizations were done using either α-methylstyryl di-tert-butyl nitroxide (A-T) as unimolecular initiator or PS macroinitiator made from A-T. These initiators allow relatively low reaction temperature (77, 87, or 97 °C) and moderate, but not eliminate, the contribution of autopolymerization or thermal initiation of polymerization. By varying unimolecular initiator concentration over nearly 4 orders of magnitude, well-controlled PS, with polydispersity index ≤ 1.4, can be made with Mn values in the range 114 000-238 000 g/mol using either A-T as initiator or a PS macroinitiator. For conditions yielding controlled PS, in general the experimental Mn-initiator concentration data afforded good agreement with the -2/3 power-law expression and allowed estimation of the equilibrium constant for the capping-uncapping reaction. However, attempts to make controlled, higher molecular weight PS by further reducing initiator concentration resulted in loss of control due to autopolymerization effects. The impact of autopolymerization in producing well-controlled PS was evident from studies yielding a nearly constant conversion as a function of macroinitiator concentration.
Stereoselective coupling of prochiral radicals with a chiral C2-symmetric nitroxide
Braslau, Rebecca,Naik, Neeta,Zipse, Hendrik
, p. 8421 - 8434 (2007/10/03)
The coupling reaction beween a chiral C2-symmetric nitroxide, trans-2,5-dimethyl-2,5-diphenylpyrrolidin-1-oxyl (DPPO; 1), and a series of stabilized secondary prochiral radicals was studied to determine the factors that affect stereoselectivity. Both steric and electronic perturbations on the selectivity by the substituents of the prochiral radical were observed. The effects of temperature, solvent polarity, and solvent viscosity were examined. High selectivity for reactions carried out in solvents of low viscosity provides evidence for the formation of an encounter complex on the reaction path. Ab initio calculations on simplified model systems predict the C-O-N angle of attack to be greater than 110°at a carbon-oxygen bond-forming distance of approximately 2.2 A, although no transition state was found.
Development of a universal alkoxyamine for "living" free radical polymerizations
Benoit, Didier,Chaplinski, Vladimir,Braslau, Rebecca,Hawker, Craig J.
, p. 3904 - 3920 (2007/10/03)
Examination of novel alkoxyamines has demonstrated the pivotal role that the nitroxide plays in mediating the "living" or controlled polymerization of a wide range of vinyl monomers. Surveying a variety of different alkoxyamine structures led to α-hydrido derivatives based on a 2,2,5-trimethyl-4-phenyl-3-azahexane-3-oxy, 1, skeleton which were able to control the polymerization of styrene, acrylate, acrylamide, and acrylonitrile based monomers. For each monomer set, the molecular weight could be controlled from 1000 to 200 000 amu with polydispersities typically 1.05-1.15. Block and random copolymers based on combinations of the above monomers could also be prepared with similar control. In comparison with 2,2,6,6-tetramethylpiperidinoxy (TEMPO), these new systems represent a dramatic increase in the range of monomers that can be polymerized under controlled conditions and overcome many of the limitations associated with nitroxide-mediated "living" free radical procedures. Monomer selection and functional group compatibility now approach those of ATRP-based systems.
Symmetrical nitroxide synthesis: Meso versus d,l diastereomer formation
Braslau, Rebecca,Chaplinski, Vladimir,Goodson, Patricia
, p. 9857 - 9864 (2007/10/03)
The syntheses of C2-symmetrical isoindoline nitroxide 2a and meso- isoindoline nitroxide 2b have been achieved by two different routes. The chiral C2-symmetric nitroxide derives from the addition of a Grignard reagent from the least hindered face opposite the large phenyl group in nitrone intermediate 21, whereas the isoindoline 3b precursor to the meso nitroxide is formed by the addition of a Grignard reagent from the face opposite the large magnesium oxide group of the tight ion pair of iminium 19. The assignment of these structures is confirmed by preparation of several derivatives as well as by X-ray crystallography.
Asymmetric Catalysis, 77. - New Optically Active Pyrazole Derivatives for Enantioselective Catalysis
Brunner, Henri,Scheck, Thomas
, p. 701 - 710 (2007/10/02)
Starting from the amines 3-6 and the dipyrazolopyrazinedione 2, the optically active (pyrazolylmethyl)amines 11-14 have been synthesized.Furthermore, the preparation of the (+)-camphor-derived optically active pyrazole 17 is described.Pyrazoles 11-13 and 17 are introduced as chiral building blocks into the 2-(1-pyrazolyl)pyridines 30-33.The optically active compounds 23-25 are formed from 2-pyridine and 2,6-bispyridine, respectively, and (+)-3-(bromomethyl)pinane.The pyrazole derivatives 27-29 contain (+)-(1-phenylethyl)hydrazine as the optically active component.Key Words: Pyrazoles, optically active / Pyridines, 2--, 2,6-bis-, 2-(1-pyrazolyl)-
