- Synthesis of a substituted benzazepin-2-one dihydrate
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Synthesis of the title compound was accomplished via coupling of (S)-alaninyl-(S)-1-amino-3-methyl-4,5,6,7-tetrahydro-2H-3-benzazepin-2-one with the activated trimethylsilyl ester of (S)-2-trimethylsilyloxy-3-methylbutyric acid, followed by deprotection a
- Boini, Sathish K.,Vaid, Radhe K.,Moder, Kenneth P.,Mitchell, David
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scheme or table
p. 1983 - 1986
(2010/01/13)
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- Asymmetric synthesis of primary amines via the spiroborate-catalyzed borane reduction of oxime ethers
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The enantioselective borane reduction of O-benzyloxime ethers to primary amines was studied under catalytic conditions using the spiroborate esters 5-10 derived from nonracemic 1,2-amino alcohols and ethylene glycol. Effective catalytic conditions were achieved using only 10% of catalyst 5 derived from diphenylvalinol in dioxane at 0°C resulting in complete conversion to the corresponding primary amine in up to 99% ee.
- Huang, Xiaogen,Ortiz-Marciales, Margarita,Huang, Kun,Stepanenko, Viatcheslav,Merced, Francisco G.,Ayala, Angel M.,Correa, Wildeliz,De Jesus, Melvin
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p. 1793 - 1795
(2008/02/02)
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- The effects of the nature of catalyst and of the solvent on the stereoselectivity in amine-catalyzed asymmetric synthesis of substituted cyclohexa-1,3-dienes from prenal and monoesters of ylidenemalonic acids
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In the amine-catalyzed reactions of prenal with (Z)-5-methyl-2-(methoxycarbonyl)hexa-2,4-dienoic or (Z)-3-phenyl-2-(ethoxycarbonyl)prop-2-enoic acid chiral β-amino alcohols provide for higher enantiomeric purity of the resulting alkyl 4-methyl-6-(2-methylprop-1-enyl)- and 4-methyl-6-phenylcyclohexa-1,3-dienoates than that provided by related chiral amines without hydroxy group. The values of ee attained in nonpolar solvents are higher than those observed in the polar ones. Substituting stoichiometric amounts of a chiral 1-amino-3-methylbuta-1,3-diene for a combination of prenal with 0.1 equiv. of the corresponding chiral amine results in the products of much lower enantiomeric purity.
- Serebryakov,Nigmatov,Shcherbakov,Struchkova
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- An efficient method for hydrolysis of N-monosubstituted amides utilization of intramolecular N---O acyl migration in hydroxypivalimides
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An efficient and versatile method for the hydrolysis of N-monosubstituted carboxamides has been developed. The method consists of two steps: the conversion to acetoxypivalimides (≥90% yield) and their mild alkaline hydrolysis (70 90% yield). No epimerization at the α-position of the acyl group took place in the process. The amine part of the original amides can be recovered in good yield.
- Tsunoda, Tetsuto,Sasaki, Osamu,Takeuchi, Osamu,Ito, Sho
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p. 3925 - 3934
(2007/10/02)
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- Evidence for an Intramolecular, Stepwise Reaction Pathway for PEP Phosphomutase Catalyzed P-C Bond Formation
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The Tetrahymena pyriformis enzyme, phosphoenolpyruvate phosphomutase, catalyzes the rearrangement of phosphoenolpyruvate to the P-C bond containing metabolite, phosphonopyruvate.To distinguish between an intra- and intermolecular reaction pathway for this process an equimolar mixture of 18O,C(2)-18O>thiophosphonopyruvate and (all 16O) thiophosphonopyruvate was reacted with the phosphonomutase, and the resulting products were analyzed by 31P NMR.The absence of the cross-over product 18O>thiophosphonoenolpyruvate in the product mixture was interpreted as evidence for an intramolecular reaction pathway.To distinguish between a concerted and stepwise intramolecular reaction pathway the pure enantiomers of the chiral substrate 18O>-thiophosphonopyruvate were prepared and the stereochemicalb course of their conversion to chiral 18O>thiophosphoenolpyruvate was determined.The assignments of the phosphorous configurations in the 18O>thiophosphonopyruvate enantiomers reported earlier (McQueney, M.S.; Lee, S.-l.; Bowman, E.; Mariano, P.S.; Dunaway- Mariano, D.J.Am.Chem.Soc. 1989, 111, 6885-6887) were revised according to the finding that introduction of the 18O label into the thiophosphonopyruvate precursor occurs with retention rather than with (the previously assumed) inversion of configuration.On the basis the observed conversion of (Sp)-18O>thiophosphonopyruvate to (Sp)-18O>thiophosphonoenolpyruvate and (Rp)-18O>thiophosphonopyruvate to (Rp)-18O>thiophosphonoenolpyruvate, it was concluded that the PEP phosphomutase reaction proceeds with retention of the phosphorus configuration and therefore by a stepwise mechanism.Lastly, the similar reactivity of the oxo- and thio-substituted phosphonopyruvate substrates (i.e., nearly equal Vmax) was interpreted to suggest that nucleophilic addition to the phosphorus atom is not rate limiting among the reaction steps.
- McQueney, Michael S.,Lee, Sheng-lian,Swartz, William H.,Ammon, Herman L.,Mariano, Patrick S.,Dunaway-Mariano, Debra
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p. 7121 - 7130
(2007/10/02)
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- CD OF PRIMARY AMINES AND 1- OR 3-SUBSTITUTED TETRAHYDROISOQUINOLINES IN PRESENCE OF
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The syntheses of (S)-(-)-1,2-dimethyl-1,2,3,4-tetrahydroisoquinoline (IX) and S-(+)-2,3-dimethyl-1,2,3,4-tetrahydroisoquinoline (XVI) in optically pure form and with known absolute configuration is described.The CD and NMR spectra of these compounds and of most of their intermediates are given, and from these data could be deduced, that the N-methyl groups of the two bases IX and XVI adopt different conformations in solution, but the same (viz. axial) in their complexes with .
- Diener, Wolfgang,Frelek, Jadwiga,Snatzke, Guenther
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p. 954 - 965
(2007/10/02)
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- Preparation of Optically Active Secondary Amines by Thermal Decomposition of (Methylbenzyl)urea Analogs: Absolute Configuration of (+) and (-)-Mecamylamine
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Thermolysis of the (α-methylbenzyl)urea diastereoisomers 4 and 5 of (+/-)-mecamylamine ((+/-)-1) and 6 and 7 of (+/-)-1-noreseroline O-methyl ether ((+/-)-3) in refluxing alcohol afforded optically pure amines in high yield, besides optically pure carbama
- Schoenenberger, Bernhard,Brossi, Arnold,George, Clifford,Flippen-Anderson, Judith L.
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p. 283 - 287
(2007/10/02)
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