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Rhodium(III)‐Catalyzed Formal Cycloaddition between Thienopyridine/Thienopyrazine Carboxylic Acids and Alkynes, Triggered by C−H Activation
Author(s) -
Rodrigues Juliana M.,
Cendón Borja,
Gulías Moisés,
Mascareñas José Luis,
Queiroz MariaJoão R. P.
Publication year - 2021
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.202100439
Subject(s) - chemistry , pyrazine , cycloaddition , catalysis , carboxylic acid , rhodium , pyridine , heteroatom , annulation , alkyne , carbonylation , combinatorial chemistry , organic chemistry , medicinal chemistry , ring (chemistry) , carbon monoxide
In the last decade, a number of metal‐catalyzed technologies for the functionalization of C−H bonds in carbonaceous aromatic substrates have been developed. However, similar reactions with aza‐heteroaromatic precursors are more challenging and have been much less developed. Herein, we report for the first time catalytic formal cycloadditions of N,S ‐heterocycles featuring carboxylic acid substituents, with unsaturated partners (alkynes). The reaction, which works with different symmetrical and unsymmetrical alkynes, produces appealing tricyclic ɑ‐pyrones in a straightforward manner. The optimized conditions established for a model reaction employing thieno[2,3‐ b ]pyridine‐2‐carboxylic acid as substrate, involved the use of Ag 2 CO 3 /AgSbF 6 as additives, and proved to be general for different alkynes. Moreover, analogous cycloadditions using thieno[3,2‐ b ]pyridine‐2‐carboxylic acid and thieno[2,3‐ b ]pyrazine‐6‐carboxylic acid were successfully developed. Overall, this catalytic technology allows to build, in a single step, an interesting variety of pharmaceutically relevant tricyclic ɑ‐pyrones exhibiting nitrogen and sulfur heteroatoms.