Abstract: The invention relates to a process which comprises reacting a compound of formula I, ##STR1## in which A.sub.1 is a radical which does not compete with the activity of the ##STR2## OR A TAUTOMER THEREOF, WITH A COMPOUND OF FORMULA II,a.sub.2 -- ch.sub.2 -- cn iiin which A.sub.2 is a radical which does not compete with the activity of the --CH.sub.2 CN group of the compound of formula II but provides the vicinal methylene group with sufficient acidity to react with the .dbd.NH group of the compound of formula I,and with sulphur,To obtain a compound of formula III, ##STR3## in which A.sub.1 and A.sub.2 are as defined above, which compounds of formula III are useful as intermediates for the production of dyestuffs.