- Convenient method for reduction of C-N double bonds in oximes, imines, and hydrazones using sodium Borohydride-Raney ni system
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(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.
- Yang, Yihua,Liu, Shouxin,Li, Junzhang,Tian, Xia,Zhen, Xiaoli,Han, Jianrong
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experimental part
p. 2540 - 2554
(2012/07/27)
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- Efficient chemoenzymatic synthesis of enantiomerically pure α-amino acids
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A general two-step chemoenzymatic synthesis for enantiomerically pure natural and nonnatural α-amino acids is presented. In the first step of the sequence, the ubiquitous educts aldehyde, amide and carbon monoxide react by palladium-catalyzed amidocarbonylation to afford the racemic N-acyl amino acids in excellent yields. In the second step, enzymatic enantioselective hydrolysis yields the free optically pure a-amino acid and the other enantiomer as the N-acyl derivative, both in optical purities of 85-99.5% ee. The advantage of the chemoenzymatic process compared to other amino acid synthesis are demonstrated by the preparation of various functionalized (-OR, -Cl, -F, -SR) α-amino acids on a 10-g scale.
- Beller, Matthias,Eckert, Markus,Geissler, Holger,Napierski, Bernd,Rebenstock, Heinz-Peter,Holla, E. Wolfgang
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p. 935 - 941
(2007/10/03)
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- Reaction of organolead triacetates with 4-ethoxycarbonyl-2-methyl-4,5-dihydro-1,3-oxazol-5-one. The synthesis of α-aryl- and α-vinyl-N-acetylglycines and their ethyl esters and their enzymic resolution
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4-Ethoxycarbonyl-2-methyl-4,5-dihydro-1,3-oxazol-5-one 7, which may be readily obtained from diethyl acetamidomalonate, undergoes high-yielding arylation and vinylation at the 4-position with organolead triacetates to give compounds which may be hydrolysed to give either the α-aryl- or α-vinyl-N-acetylglycine or the corresponding ethyl ester. The kinetic resolution of a number of these derivatives by enzymic hydrolysis of either the amide or ester function has been demonstrated.
- Morgan, Jacqueline,Pinhey, John T.,Sherry, Christopher J.
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p. 613 - 619
(2007/10/03)
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- Reaction of Organolead Triacetates with 4-Ethoxycarbonyl-2-methyloxazol-5-one. The Synthesis of α-Aryl and α-Vinyl N-Acetylglycine Ethyl Esters and Their Enzymic Resolution.
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An efficient synthesis of the moisture-sensitive compound, 4-ethoxycarbonyl-2-methyloxazol-5-one, has been achieved.This compound undergoes high-yielding arylation and vinylation at the 4-position with organolead triacetates to give compounds which in water are converted to α-aryl and α-vinyl N-acetylglycine ethyl esters.These α-substituted glycine derivatives may be kinetically resolved in very good yield and high enantiomeric excess by enzymic hydrolysis of either the ester group or the amide function of the corresponding carboxylic acids.
- Morgan, Jacqueline,Pinhey, John T.
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p. 9625 - 9628
(2007/10/02)
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- HOMOCHIRAL HETEROORGANIC ANALOGS OF NATURAL COMPOUNDS. I. PREPARATIVE BIOCATALYTIC METHOD OF OBTAINING FLUORINE-CONTAINING L- AND D-PHENYLGLYCINES
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A biocatalytic method of obtaining homochiral o- and p-fluorine-substituted phenylglycines by enantiomeric hydrolysis from N-phenylacetyl or N-acetyl derivatives under the action of Escherichia coli penicillin acylase or Streptoverticillium olivoreticuli aminoacylase is proposed.The L form of the amino acid and the unhydrolyzed D-enantiomer of the initial derivative are separated by extraction and chromatographic methods.The acid hydrolysis of the D-enantiomers of N-phenylacetyl derivatives of fluorine-substituted phenylglycines leads to partial (about 15percent) racemization.With a substantially higher (by two orders of magnitude) concentration of enzyme and an increase in the reaction time it is possible to use penicillinase as a catalyst for the hydrolysis of the D-enantiomer of the N-phenylacetyl derivative not accompanied by any appreciable racemization whatever.
- Soloshonok, V. A.,Galaev, I. Yu.,Shvyadas, V. K.,Kozlova, E. V.,Kotik, N. V.,et al.
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p. 228 - 232
(2007/10/02)
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