Amino Acids 2010 Jan 12;38(1):305-10. Epub 2009 Feb 12.
Dipartimento di Chimica Organica e Biochimica, Università di Napoli Federico II, 80126, Naples, Italy.
The synthesis of new substituted prolines carrying at C-4 a second alpha-amino acid residue is reported. The amino acid, L-cysteine or L-selenocysteine, is linked to the proline ring through the sulfur or the selenium atom, respectively. The products were prepared with different stereochemistry at C-4, in few and clean high-yielding steps, with suitable protections for solid phase applications. The introduction of both sulfur and selenium atoms at C-4 of the proline ring seems to enhance significantly the cis geometry at the prolyl amide bond.