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Chemistry of thienopyridines. XVII. Direct halogenation of thieno[2,3‐ b ]pyridine
Author(s) -
Klemm L. H.,
Merrill R. E.,
Lee F. H. W.,
Klopfenstein C. E.
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.5570110218
Subject(s) - chemistry , chloroform , halogenation , pyridine , bromine , halogen , yield (engineering) , chlorine , medicinal chemistry , sulfuric acid , organic chemistry , alkyl , materials science , metallurgy
Thieno [2,3‐ b ] pyridine (Ia) was converted into its 3‐chloro, 3‐bromo, and 3‐iodo derivatives by means of elemental halogen, silver sulfate, and sulfuric acid. Bromine in a buffered chloroform solution of la also gave the 3‐bromo compound (57% yield). Chlorine plus a refluxing mixture of Ia, chloroform, and water produced both the 3‐chloro and the 2,3‐dichloro derivatives. Various transformation products of these halothienopyridines (including the 2‐nitro‐3‐halo compounds) are described and mass spectral fragmentation patterns are presented.