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Quinoline syntheses by reaction of hydrazoic acid with α,β‐disubstituted cis ‐chalcones
Author(s) -
Pratt Robert E.,
Welstead William J.,
Lutz Robert E.
Publication year - 1970
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.5570070508
Subject(s) - hydrazoic acid , chemistry , quinoline , sulfuric acid , isoquinoline , medicinal chemistry , ring (chemistry) , benzophenone , nitrogen , organic chemistry
Hydrazoic‐sulfuric acid mixture converted cis ‐α‐phenyl‐β‐benzoylchalcone ( trans ‐dibenzoylstilbene, 4 ) into 2,3‐diphenyl‐4‐benzoylquinoline ( 5 ) the structure of which was proved by debenzoylation to 2,3‐diphenylquinoline. α,β‐Diphenyl and cis ‐α,β‐dibromochalcones similarly were converted respectively into 2,3,4‐triphenylquinoline ( 19 ) and 2‐phenyl‐3,4‐dibromoquinoline ( 20 ). The structure of 19 was shown by difference from the corresponding isoquinoline 21 (synthesized). Smith's mechanism for the analogous conversion of o ‐phenylbenzophenone into 9‐phenylphenanthridine through the 9‐fluorenol and the 9‐hydroazide with loss of nitrogen and ring expansion, was supported by methyl label experiments using 2‐( p ‐tolyl)benzophenone which gave a 53:47 mixture of 3‐ and 8‐methyl‐6‐phenylphenanthridines. Applicability of the mechanism to the reactions with disubstituted cis ‐chalcones was shown by sulfuric acid conversions of two of these into indenol 22 and 2‐bromo‐3‐phenylindenone ( 24 ), respectively. trans ‐Dibenzoylstilbene underwent resinification in sulfuric acid, giving the quinoline ( 5 ) only when hydrazoic acid was present.