Functionalised polysulphide synthesis method

1. A process comprising the steps of:

(a) providing O-acetyl L-serine, O-phospho L-serine, or O-acetyl L-homoserine;

(b) providing at least one inorganic polysulfide;

(c) reacting the O-acetyl L-serine, O-phospho L-serine, or O-acetyl L-homoserine with the at least inorganic polysulfide in the presence of O-acetyl L-serine sulfhydrylase, O-phospho L-serine sulfhydrylase, or O-acetyl L-homoserine sulfhydrylase;

(d) obtaining at least one functionalized organic polysulfide of formula (I):

R 2 —X—(NR 1 R 7 )C*H—(CH 2 ) n —S a —(CH 2 ) n —C*H(NR 1 R 7 )—X—R 2   (I)

wherein:

R 1 is a hydrogen atom and R 7 is a hydrogen atom;

X is —C(═O)—;

R 2 is —OR 3 , where R 3 is a hydrogen or a hydrocarbon containing 1 to 20 carbon atoms that can also contain heteroatoms, the hydrocarbon being aromatic or nonaromatic, linear or cyclic, saturated or unsaturated, branched or unbranched;

n is 1 or 2;

a is an integer between 2 and 10; and

C* represents an asymmetric carbon;

(e) separating and isolating the at least one functionalized organic polysulfide of formula (I); and

(f) optionally, adding functional groups different to those obtained in stage (d) or stage (e);

wherein stages (a) and (b) are carried out simultaneously or sequentially.

2. The process as claimed in claim 1 , wherein the functionalized organic polysulfide of formula (I) is enantiomerically pure.

3. The process as claimed in claim 1 , wherein the functionalized organic polysulfide of formula (I) is chosen from dicysteine polysulfide and dihomocysteine polysulfide.

4. The process as claimed in claim 1 , wherein the inorganic polysulfide contains an alkali metal, an alkaline earth metal or an ammonium group.