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Chemistry of Thienopyridines. XXIV. Two Transformations of Thieno[ 2,3‐b] pyridine 7‐Oxide
Author(s) -
Ktemm L. H.,
Hartling Ross
Publication year - 1976
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.5570130610
Subject(s) - chemistry , pyridine , isomerization , medicinal chemistry , hydrolysis , pyridine n oxide , oxide , mass spectrum , organic chemistry , catalysis , ion
Refluxing thieno[2,3‐b ]pyridine 7‐oxide ( 1 ) with aeetic anhydride plus subsequent hydrolysis produced a mixture of thieno[2,3‐b]pyrid‐6(7 H )one ( 2 ) (13%) and 5‐hydroxythieno[2,3‐b]‐pyridine ( 4 ) (4%). Refluxing 1 with phosphorus oxychloride yielded a mixture of 4‐ and 6‐chloro‐thieno[2,3‐b]pyridines, ( 5 ) (54%) and ( 6 ) (31%), respectively. Compound 6 was also obtained directly from 2 (31%). A mechanistic rationalization for the isomerization of 1 to form 2 and 4 is presented. Marked differences in the mass spectral fragmentations of these three isomeric compounds are noted.