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Your search keyword '"Tamayo, JA"' showing total 2 results
Start Over Author "Tamayo, JA" Journal organic biomolecular chemistry
2 results on '"Tamayo, JA"'

1. Diastereoselective synthesis of quaternary alpha-amino acids from diketopiperazine templates.

Author

Davies SG, Garner AC, Ouzman JV, Roberts PM, Smith AD, Snow EJ, Thomson JE, Tamayo JA, and Vickers RJ

Subjects
Alkylation, Amino Acids chemistry, Crystallography, X-Ray, Diketopiperazines, Hydrolysis, Lactams chemistry, Methylation, Models, Molecular, Molecular Structure, Protons, Stereoisomerism, Amino Acids chemical synthesis, Piperazines chemistry
Abstract

Sequential enolate alkylations of (S)-N(1)-methyl-5-methoxy-6-isopropyl-3,6-dihydropyrazin-2-one and (S)-N(1)-p-methoxybenzyl-5-methoxy-6-isopropyl-3,6-dihydropyrazin-2-one proceed with excellent levels of diastereoselectivity (>90% de) affording quaternary alpha-amino acids in high enantiomeric excess (>98% ee) after deprotection and hydrolysis.

Published
2007
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2. Asymmetric conjugate reductions with samarium diiodide: asymmetric synthesis of (2S,3R)- and (2S,3S)-[2-2H,3-2H]-leucine-(S)-phenylalanine dipeptides and (2S,3R)-[2-(2)H,3-2H]-phenylalanine methyl ester.

Author

Davies SG, Rodriguez-Solla H, Tamayo JA, Cowley AR, Concellon C, Garner AC, Parkes AL, and Smith AD

Subjects
Crystallography, X-Ray, Dipeptides chemistry, Magnetic Resonance Spectroscopy, Molecular Structure, Oxidation-Reduction, Phenylalanine chemical synthesis, Phenylalanine chemistry, Stereoisomerism, Dipeptides chemical synthesis, Iodides chemistry, Phenylalanine analogs & derivatives, Samarium chemistry
Abstract

The highly diastereoselective samarium diiodide and D(2)O-promoted conjugate reduction of homochiral (E)- and (Z)-benzylidene and isobutylidene diketopiperazines (E)-5,7 and (Z)-6,8 has been demonstrated. This methodology allows the asymmetric synthesis of methyl (2S,3R)-dideuteriophenylalanine 27 in > or = 95% de and >98% ee, and (2S,3R)- or (2S,3S)-dideuterioleucine-(S)-phenylalanine dipeptides 37 and 38 in moderate de, 66% and 74% respectively. A mechanism is proposed to account for this process.

Published
2005
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