2-Methylbenzimidazole 1 reacted with 3-dicyanomethylidine-
1-ethyl-2-oxoindoline 2 in ethyl acetate to
afford 1-amino-2-cyano-3,4-dihydro-10-ethylspiro{benzimidazo[
1,2-a]pyridine-3,30-indolin}-20-one 6, which was
used as a key intermediate in the synthesis of fused
spiropolyheterocyclic derivatives of benzimidazopyridopyrimidine
and/or benzimidazonaphthyridine nucleus
incorporating an indoline moiety