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Polycondensed heterocycles. II. A new preparative route to 11‐Oxo‐5 H ,11 H ‐pyrrolo[2,1‐ c ][1,4]benzothiazepine
Author(s) -
Nacci V.,
Garofalo A.,
Fiorini I.
Publication year - 1986
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570230324
Subject(s) - chemistry , pyrrole , cyanation , demethylation , isoquinoline , bromide , medicinal chemistry , nitrile , chloride , organic chemistry , catalysis , biochemistry , gene expression , dna methylation , gene
6‐Methylthio‐10‐oxo‐5 H ,10 H ‐pyrrolo[1,2‐ b ]isoquinoline 11 was isolated in an attempted synthesis of 11‐oxo‐5 H ,11 H ‐pyrrolo[2,1‐ c ][1,4]benzothiazepine 1 from 1‐(2‐methylthiobenzyl)pyrrole‐2‐carboxylic acid chloride 9 , obtained using as starting material o ‐methylthiobenzyl bromide 3 and passing through 1‐(2‐methylthiobenzyl)pyrrole‐2‐carbonitrile 5 , by cyclization with aluminum chloride. However the successful demethylation with sodium in dimethylacetamide of 1‐(2‐methylthiobenzyl)pyrrole‐2‐carboxyamide 12 , formed by hydrolysis of nitrile 5 , allowed us to prepare by another way the corresponding thiol 13 and consequently the 1‐(2‐mercaptobenzyl)pyrrole‐2‐carboxylic acid 14 , which when subjected to intramolecular ring closure by CDI in place of DCC gave 1 in higher yield, 69% instead of 43%. Finally, the direct cyanation of 1‐(2‐ethoxycarbonylthiobenzyl)pyrrole 16 , prepared utilizing the 1‐(2‐mercaptobenzyl)pyrrole 15 obtained by demethylation of the corresponding thioanisol 4 which was carried out as above, afforded the unexpected 1‐(2‐ethylthio‐benzyl)pyrrole‐2‐carbonitrile 17 .