The amonolysis of trifluoroacetonitrile (I) in refluxing liquid ammonia gives trifluoroacetamidine (II), which by reaction with SH2 in ether is converted into trifluorothioacetamide (III). Finally, this compound is cyclized with p-methoxy-alpha-bromo-alpha-(p-methoxyphenyl)acetophenone (IV) in refluxing acetonitrile.