| abstract |
A process for the preparation of a compound of formula (I), or a salt thereof n n n wherein R is H, C 1 -C 8 alkyl, aryl or aryl-C 1 -C 8 alkyl; comprising the reaction between a compound of formula (II) n n n wherein R 1 and R 2 are independently hydrogen, C 1 -C 8 alkyl, aryl, aryl-C 1 -C 8 alkyl, or R 1 and R 2 , taken together, form a —(CH 2 ) m —V—(CH 2 ) n — group, in which V is NR 3 or C(R 3 ) 2 wherein R 3 is hydrogen, C 1 -C 8 alkyl, aryl or aryl-C 1 -C 8 alkyl; and m and n, which can be the same or different, are 1 or 2; with a compound of formula (III) n n n in which R 4 and R 5 are independently C 1 -C 8 alkyl, aryl or aryl-C 1 -C 8 alkyl; in the presence of a Ni (II) salt, an organic ligand and a basic agent, to obtain a compound of formula (I) wherein R is C 1 -C 8 alkyl, aryl or aryl-C 1 -C 8 alkyl and, if desired, its conversion to a compound of formula (I) wherein R is hydrogen or to a salt thereof. |