Studies on the syntheses of heterocyclic compounds. Part DCXXXII . The formation of the benzimidazo[2,1‐ a ]isoquinoline by reaction of the 1,2,3,4‐tetrahydro‐1‐(2‐nitrophenethyl)isoquinoline with triethyl phosphite

Reductive cyclization of 1,2,3,4‐tetrahydro‐6,7‐dimethoxy‐1‐(4,5‐dimethoxy‐2‐nitrophen‐ethyl)isoquinoline (V) with triethyl phosphite gave 5,6‐dihydro‐2,3,9,10‐tetramethoxybenzimidazo[2,1‐ a ]isoquinoline (IX), whose structure was identified by the spectroscopic analyses by an alternative synthesis.