Patent ID: 8835477

Claim:
A method for the synthesis of a 2-thiohistidine derivative of the following formula (I): or a physiologically acceptable salt, a tautomer, a stereoisomer or a mixture of stereoisomers in any proportions thereof, wherein: R 1 and R 2 represent, independently of each other, a hydrogen atom or a (C 1 -C 4 )alkyl group, at least one of the groups R 1 and R 2 representing a hydrogen atom, and R 3 and R 4 represent, independently of each other, a hydrogen atom or a (C 1 -C 4 )alkyl group, comprising the following successive steps: (i) performing a cleavage reaction of a compound of following formula (II): or a physiologically acceptable salt, a tautomer, a stereoisomer or a mixture of stereoisomers in any proportions thereof, wherein: represents R 1 , R 2 , R 3 and R 4 are such as defined above, R 5 represents a hydrogen atom or a (C 1 -C 4 )alkyl or —CO—((C 1 -C 4 )alkyl) group, and R 6 represents a hydrogen atom or a (C 1 -C 4 )alkyl group, in the presence of a thiol, at a temperature higher than or equal to 60° C., to yield a compound of the formula (I), and (ii) separating the compound of the formula (I) obtained in the preceding step (i) from the reaction medium.