Catalytic asymmetric synthesis of protected tryptophan regioisomers.
Tryptophan 1 (Trp) is superior to all other naturally occurring peptide residues in its ability to bind cations (the cation-pi interaction). In an effort to expand the toolbox of Trp-like amino acids, in this note we report catalytic asymmetric syntheses of Trp regioisomers 2a-e, where the alanine unit is attached not to C-3 of indole but to C-2, C-4, C-5, C-6, or C-7. Excellent asymmetric induction is obtained in each case (generally >97% ee). Ab initio calculations suggest that the indole nuclei of 2a-e will bind Na(+) with the same affinity as that of Trp.
Carlier
Paul R
PR
Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, USA. pcarlier@vt.edu
Lam
Polo C-H
PC
Wong
Dawn M
DM
D002384:Catalysis; D002412:Cations / Q000737:chemistry; D002625:Chemistry, Organic / Q000379:methods*; D006865:Hydrogenation; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry; D008968:Molecular Conformation; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*; D011485:Protein Binding; D013237:Stereoisomerism; D014364:Tryptophan / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000737:chemistry
D002412:Cations; D007211:Indoles; D010455:Peptides; D014364:Tryptophan