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A Facile Synthesis of [1]Benzopyrano[4,3‐ b ]pyridin‐5‐ones
Author(s) -
Ivano Ivo C.,
Karagiosov Stoyan K.,
Simeonov Mario F.
Publication year - 1992
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.199219920138
Subject(s) - formylation , chemistry , piperidine , condensation , medicinal chemistry , stereochemistry , organic chemistry , catalysis , physics , thermodynamics
The title compounds 5a ‐ c and 7a ‐ m have been prepared by Vilsmeier formylation of 4‐aminocoumarins 1 yielding aldehydes 2 , and subsequent condensation of 2 with C‐H acids in the presence of piperidine. This condensation probably proceeds via the intermediate ylidenemalonic esters 4 . By means of detailed 1 H‐ and 13 C‐NMR studies a Dimroth‐type rearrangement of intermediates 6f ‐ m has been found to take place in the course of the formation of products 7f‐m .