5-Arylazo-3-phenyl-4-thiohydantoins (IIa-g) have been prepared
and then treated with primary aromatic amines to afford the
corresponding 5-arylazo-4-arylimino-3-phenyl hydantoins (VIIa-c).
3-Phenyl-4-thiohydantoin reacted with aromatic aldehydes in the
presence of glacial acetic acid and fused sodium acetate to give
5-arylidene-3-phenyl-4-thiohydantoin derivatives (VIIIa-e). In the
coloured arylidene derivatives (VIII,a d, e) on treatment with alkyland/
or arylmagnesium halide addition occurs to the exocyclic
double bond to give the products (IXa-e). The Grignard product
(Xa) was oxidised with a mixture of chromic acid in glacial acetic
acid to give phenyl parabanic acid and ethyl phenyl ketone
