Process for the preparation of S-alkylcysteines

A process for the preparation of S-alkylcysteines of formula ##STR4## wherein R is a linear or branched C.sub.1 -C.sub.4 alkyl group;

• the carbon atom marked by the asterisk is a stereogenic centre;
• comprising the treatment of a compound of formula ##STR5## wherein R.sub.1 is hydrogen or a linear or branched C.sub.1 -C.sub.6 aliphatic acyl group, or an arylcarbonyl group, or an alkoxycarbonyl or aryloxycarbonyl group, wherein the alkyl moiety is a linear or branched C.sub.1 -C.sub.4 alkyl, optionally substituted;
• R.sub.2 is a hydrogen atom or an optionally substituted linear or branched C.sub.1 -C.sub.6 alkyl or an optionally substituted benzyl group;
• wherein the carbon atom marked by the asterisk has the above reported meaning;
• with a dialkylcarbonate of formula
• (RO).sub.2 CO (III)
• wherein
• R has the above reported meanings;
• in the presence of a suitable organic or inorganic base;
• and the optional hydrolysis reaction, when one or both R.sub.1 and R.sub.2 are different from hydrogen.