- Design and synthesis of a s-triazene based asymmetric organocatalyst and its application in enantioselective alkylation
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A very efficient chiral organocatalyst was prepared from the readily available cyanuric chloride. The asymmetric catalyst exhibited a highly enantioselective catalytic performance for the alkylation of a glycinate Schiff base, which provides a useful procedure for the enantioselective synthesis of structurally diverse natural and unnatural α-alkyl-α-amino acids.
- Mangawa, Shrawan K.,Singh, Ashawani K.,Awasthi, Satish K.
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p. 61144 - 61147
(2015/08/03)
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- A New Chiral Glycine Synthon. Synthesis, X-Ray Structure of (-)-(2S,4R)-2-Ethoxycarbonyl-4-phenyl-1,3-oxazolidine and Diastereoselective Nucleophilic Ring Opening to (R)-Ethyl α-Amino Carboxylates.
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Condensation of (R)-N-benzyl-2-phenylglycinol 1 with the methyl hemiacetal of ethyl glyoxylate leads to (2S,4R)-2-ethoxycarbonyl-4-phenyl-1,3-oxazolidine 2 as the major product, obtained as a pure enantiomer after column chromatography.Compound 2 is stereoselectively cleaved by dialkylzinc reagents, prepared from alkylmagnesium iodides and ZnCl2, with moderate to good d.e. (72-94 percent).These compounds, after separation by column chromatography and debenzylation by hydrogenolysis in the presence of 10percent Pd on carbon, lead to enantiomerically pure ethyl α-amino carboxylates with good chemical yields. Key words: Chiral Oxazolidines, alpha-amino Esters, Chiral Glycine Synthon, Ring Opening, Asymmetric Synthesis
- Andres, Celia,Gonzalez, Alfonso,Pedrosa, Rafael,Perez-Encabo,Garcia-Granda, Santiago,et al.
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p. 4743 - 4746
(2007/10/02)
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