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Synthesis of New Thieno[3, 2‐ b ]pyridines and Thieno[2, 3‐ b ]pyrazines by Palladium Cross‐Coupling.
Author(s) -
Campos Joana F.,
Queiroz Maria João R. P.,
BerteinaRaboin Sabine
Publication year - 2017
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201701054
Subject(s) - pyrazine , chemistry , phenylacetylene , sonogashira coupling , pyridine , aryl , palladium , halogenation , medicinal chemistry , suzuki reaction , combinatorial chemistry , coupling reaction , catalysis , organic chemistry , alkyl
Several new 3‐(hetero)aryl‐2‐phenylthieno[3, 2‐ b ]pyridines and 7‐(hetero)aryl‐6‐phenyl thieno[2, 3‐ b ]pyrazines were prepared by Suzuki cross‐coupling of 3‐bromo‐2‐phenylthieno[3, 2‐ b ]pyridine and 7‐bromo‐6‐phenylthieno[2, 3‐ b ]pyrazine and (hetero)arylboronic acids after optimization of the reaction conditions, in moderate to excellent yields. The 3‐ and 7‐brominated compounds were prepared by bromination using Br 2 in CH 2 Cl 2 at 0 °C of the 2‐phenylthieno[3, 2‐ b ]pyridine and 6‐phenylthieno[2, 3‐ b ]pyrazine, respectively. The latter were synthesized in a two‐step one‐pot procedure by Pd/Cu catalyzed Sonogashira coupling of 2‐bromo‐3‐chloropyridine or 2,3‐dichloropyrazine with phenylacetylene, followed by treatment with Na 2 S. We show the wide scope of the synthesis of Suzuki cross‐coupling products, after optimization of the reaction conditions, from both brominated biheterocyclic systems and different (hetero)arylboronic acids. The final compounds may show interesting biological activity.