Synthesis of novel benzo[b]pyrimido[4',5':5,4]thieno[2,3-e][1,6]naphthyridine-8-ones via Pictet–Spengler cyclization

An efficient method for the synthesis of novel benzob]pyrimido4',5':5,4]thieno2,3e]-1,6]naphthyridine-8-one derivatives via Pictet–Spengler cyclization is reported. The reaction of 4-(3-aminopyrimido4,5-d]thieno-2-yl)quinoline-2-ones, which could be obtained from Thorpe–Ziegler isomerization of 4-bromomethylquinoline-2-ones and 5-cyano-1,6-dihydro-4-methyl-2-phenyl-6-thioxopyrimidine,with aromatic aldehydes in the presence of BF_3·OEt_2 gives pyrimidothieno1,6]naphthyridines in good yields.

Synthesis of novel benzo[b]pyrimido[4',5':5,4]thieno[2,3-e][1,6]naphthyridine-8-ones via Pictet-Spengler cyclization

An efficient method for the synthesis of novel benzob]pyrimido4',5':5,4]thieno2,3e]-1,6]naphthyridine-8-one derivatives via Pictet-Spengler cyclization is reported. The reaction of 4-(3-aminopyrimido4,5-d]thieno-2-yl)quinoline-2-ones, which could be obtained from Thorpe-Ziegler isomerization of 4-bromomethylquinoline-2-ones and 5-cyano-1,6-dihydro-4-methyl-2-phenyl-6-thioxopyrimidine, with aromatic aldehydes in the presence of BF₃ OEt₂ gives pyrimidothieno1,6]naphthyridines in good yields.