Download full text in PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... New uses of the westphal condensation. Synthesis of pi-donor-pi-acceptor heterocycles. ... Novel pyrido[1,2-a] and pyridazino[2,3-a]-pyrrolo[2,1-c]pyrazin-7-ium derivatives have been prepared using Westphal condensation as an example of fused heterocycles with linked π-donor ...