New conjugated systems derived from piperazine-2,5-dione

Abstract

The preparation of monoarylidene and both symmetrical and unsymmetrical bis-arylidene derivatives of piperazine-2,5-dione is described. The use of 1,4-diacetyl-piperazine-2,5-dione make it possible to prepare unsymmetrical bisarylidenes. The introduction of a dicyanomethylene moiety into the para position of one of the arylidene groups gave a remarkable deepening in the colour of the resulting compounds 11 and 16.