Synthesis of 5H-chromeno[3,4-b]pyridines via DABCO-catalyzed [3 + 3] annulation of 3-nitro-2H-chromenes and allenoates

The DABCO-catalyzed [3 + 3] annulation between 3-nitro-2H-chromenes and benzyl 2,3-butadienoate has been developed as a route to 5H-chromeno[3,4-b]pyridine derivatives. Under optimal reaction conditions, 5H-chromeno[3,4-b]pyridines incorporating two allenoate units were obtained in moderate to good...

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Bibliographic Details
Published in:Organic & biomolecular chemistry 2021-11, Vol.19 (44), p.9711-9722
Main Authors: Soares, Maria I L, Gomes, Clara S B, M Conceição Oliveira, Marçalo, Joaquim, Teresa M V D Pinho e Melo
Format: Article
Language:English
Subjects:
Allene
Chemical reactions
Intermediates
Mass spectrometry
Mass spectroscopy
Organic chemistry
Pyridines
Reaction mechanisms
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Summary:The DABCO-catalyzed [3 + 3] annulation between 3-nitro-2H-chromenes and benzyl 2,3-butadienoate has been developed as a route to 5H-chromeno[3,4-b]pyridine derivatives. Under optimal reaction conditions, 5H-chromeno[3,4-b]pyridines incorporating two allenoate units were obtained in moderate to good yields (30–76%). The same type of transformation could be carried out using butynoates as allene surrogates. Mechanistic studies by mass spectrometry allowed the identification of the key intermediates involved in the reaction mechanism. The reported synthetic methodology represents an entirely new approach for the synthesis of the 5H-chromeno[3,4-b]pyridine core structure based on allene chemistry.
ISSN:1477-0520
1477-0539
DOI:10.1039/d1ob01130h