Categories: C-C Bond Formation > Nitrogen-containing molecules >
Synthesis of α-Amino Acids and Derivatives
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Recent Literature
A Zn/Cu(OTf)2-mediated addition of alkyl bromides to
dehydroalanine (Dha) derivatives including dipeptides and tripeptides provides
selective and biocompatible access to various amino acid units in good to high
yields in an aqueous medium.
J.-A. Shin, J. Kim, H. Lee, S. Ha, H.-Y. Lee, J. Org. Chem., 2019, 84,
4558-4565.
By condensing α-3° primary amines with an electron-rich aryl aldehyde, an
oxidation and deprotonation event is enabled, which generates a key imidoyl
radical intermediate. A subsequent β-scission event liberates alkyl radicals for
coupling with electron-deficient olefins for the generation of unnatural
γ-quaternary amino acids and other valuable synthetic targets.
M. A. Ashley, T. Rovis, J. Am. Chem. Soc.,
2020, 142, 18310-18316.
Rhodium-catalyzed conjugate addition of potassium trifluoro(organo)borates to
dehydroalanine derivatives, using chiral ligands such as fluorophos and in situ
enantioselective protonation with guaiacol (2-methoxyphenol), afforded a variety
of protected α-amino esters with high yields and enantiomeric excesses up to
95%.
L. Navarre, R. Martinez, J.-P. Genet, S. Darses, J. Am. Chem. Soc., 2008,
130, 6159-6169.
Potassium trifluoro(organo)borates, which are highly stable and easily
prepared organoboron derivatives, were able to react with various
dehydroamino esters to alanine derivatives in good to high yields. This
reaction, catalyzed by rhodium complexes, tolerates a great variety of amino
protecting groups.
L. Navarre, S. Darses, J.-P. Genet, Eur. J. Org. Chem., 2004,
69-73.
Photoinduced decatungstate-catalyzed Giese reactions of readily available
aldehydes as radical precursors with dehydroalanine provide γ-carbonyl α-amino
acids. This mild, robust method is compatible with a wide array of functional
groups and has a broad substrate scope.
X. Wang, Y. Chen, H. Song, Y. Liu, Q. Wang, Org. Lett., 2021, 23,
2199-2204.
A visible-light-enabled, photocatalyst-free conjugate addition of
4-acyl-1,4-dihydropyridines to dehydroamino acids provides β-acyl α-amino acids
and their deuterated analogues in good yields. 4-Acyl-1,4-dihydropyridines serve
both as a radical reservoir and reductant. The reaction can be used for
late-stage peptide modification and stereoselective synthesis of chiral
oxazolidinones.
L. Liu, Z. Deng, K. Xu, P. Jiang, H. Du, J. Tan, Org. Lett., 2021, 23,
5288-5293.
The generation of α-fluoroalkyl or fluorobenzyl radicals from readily
available α-fluorocarboxylic acids under mild reaction conditions and their
utilization in the Giese-type addition on Michael acceptors and dehydroamino
acids provides mono- and difluorinated Michael addition adducts and unnatural
fluorinated amino acids.
A. Gutiérrez-Bonet, W. Liu, Org. Lett., 2023, 25,
483-487.
An iron-catalyzed alkylazidation of dehydroamino acids using peroxides as
alkyl radical precursors provides α-alkyl-α-azide α-amino esters in good yields
using TMSN3 as an azide source. The products could be further
functionalized through cycloaddition or azide reduction with amide couplings to
afford aminal-type peptides, α-triazolo amino acids, and a
tetrahydro-triazolopyridine.
P. Palamini, E. M. D. Allouche, J. Waser, Org. Lett., 2023, 25,
6791-6795.