SYNTHESIS OF THIAOLIVACINE AND RELATED COMPOUNDS

1,5‐Dimethylbenzothieno[2,3‐g]isoquinoline (thiaolivacine) has been prepared from the nitro‐vinyl derivative of 4‐methyl‐3‐dibenzothiophenecarboxaldehyde. Using the same aldehyde, 4‐des‐methylisothiaolivacine was prepared by formation of the Schiff's base with aminoacetaldehyde diethyl acetal followed by cyclization. Similar methods yielded the pyrido‐N‐isomer, 1‐des‐methylthiaolivacine, from 4‐methyl‐2‐dibenzothiophenecarboxaldehyde. The thiaolivacine parent unsubstituted ring system, benzothieno[2,3‐g]isoquinoline, was prepared from 2‐dibenzothio‐pheneearboxaldehyde by the aminoacetaldehyde approach, as was the corresponding oxygen analog, benzofuro[2,3‐g]isoquinoline, from 2‐dibenzofurancarboxaldehyde. The 100 MHz spectra of these fused isoquinolines are recorded and correlated. Copyright © 1969 Journal of Heterocyclic Chemistry