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Novel polycyclic heterocycles. XI. Synthesis of 11,12‐dihydropyrido[2,1‐ b ] [1,3]benzodiazepines, 6 H ‐pyrido[1,2‐ c ] [1,3,5]benzoxadiazepines, and 6 H ‐Pyrido[1,2‐ c ] [1,3,5]benzothiadiazepines
Author(s) -
Petigara R. B.,
Yale Harry L.
Publication year - 1974
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.5570110312
Subject(s) - chemistry , potassium carbonate , anhydrous , pyridine , methanol , medicinal chemistry , bromine , ring (chemistry) , catalysis , stereochemistry , organic chemistry
An unusually facile dehydrobromination, involving the ortho ‐bromine atom and the = NH proton of a 2‐imino‐1‐(phenethyl)‐, 2‐imino‐1‐(phenoxymethyl)‐, or 2‐imino‐1‐(phenylthiomethyl)‐pyridine ( 2a‐e ) has led to the synthesis of three novel bridgehead nitrogen tricyclic systems: 11,12‐dihydropyrido[2,1‐ b ] [1,3]benzodiazepines ( 3a,b ), 6 H ‐pyrido[1,2‐ c ] [1,3,5]benzoxadiazepines ( 3c,d ) and 6 H ‐pyrido[1,2‐ c ][1,3,5]benzothiadiazepines ( 3e ). As anticipated, these cyclizations required a base, e.g. , potassium carbonate, and a catalyst, e.g. , copper bronze. What was unusual, was that these reactions occurred in methanol or n ‐propanol, under reflux, either under anhydrous conditions, or in the presence of large amounts of water. The pmr spectra of these compounds are discussed.