Synthesis of New Gold(I) Thiolates Containing Amino Acid Moieties with Potential Biological Interest

The
reaction of the gold­(I) complex [Au­(SpyCOOH)­(PPh3)], which
contains nicotinic acid thiolate, with several amino acid
esters such as glycine methyl ester or the enantiomerically pure l isomers of alanine methyl ester, phenylalanine methyl ester,
valine
methyl ester, methionine methyl ester, and proline methyl ester produces
the gold­(I) derivatives with the new thiolate containing amino acid
ester ligands [Au­{SpyCONHCH­(R)­COOMe}­(PPh3)]. The reaction
of these amino acid ester derivatives with LiOH in methanol and acidification
with KHSO4 until pH 3–4 afford the corresponding
acids, which are water-soluble species. These amino acid compounds
can be further coupled with
other amines, such as, for example, isopropylamine, to give the corresponding
amide derivatives. The species with glycine methyl ester and valine
methyl ester have been characterized by X-ray crystallography, showing,
in the second case, only one of the enantiomers, which proves that
retention of the configuration after reaction occurs.