SYNTHESIS OF PYRROLO[2,1-F][1,2,4]TRIAZINE CONGENERS OF NUCLEIC-ACID PRUINES VIA AND N-AMINATION OF 2-SUBSTITUTED PYRROLES

The synthesis of several new 4-mono- and 2,4-disubstituted pyrrolo[2,1 -f][1,2,4]triazines is described. Key 1-aminopyrrole-2-carbonitrile in termediates 3 and 15 were obtained by N-amination of the corresponding pyrrole-2-carboxaldehyde followed by CHO --> CN conversion with eithe r hydroxylamine-O-sulfonic acid for 3 or O-mesitylenesulfonylhydroxyla mine for 15. Cyclization of 3 or 15 with a variety of amidine reagents or, after conversion of 3 to its corresponding amide, base-catalyzed annulation completed the synthesis of the title products.