(3+3) Annulation of acetoxy allenoates with enolisable carbonyl substrates leading to fused pyrans

Lewis base dependent (3 + 3) annulation of delta-acetoxy allenoates with benzofuranone, pyrazolone, and Boc-protected oxindole is reported. In the presence of catalytic DBU, oxindole, benzofuranone, and pyrazolone undergo (3 + 3) annulation with delta-acetoxy allenoates via 6-exo-dig cyclisation at...

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Bibliographic Details
Published in:Organic & biomolecular chemistry Vol. 21; no. 24; pp. 5021 - 5032
Main Authors: Chauhan, Sachin, Debnath, Shubham, Swamy, K. C. Kumara
Format: Journal Article
Language:English
Published: CAMBRIDGE Royal Soc Chemistry 21.06.2023
Subjects:
Chemistry
Chemistry, Organic
Physical Sciences
Science & Technology
ISSN:1477-0520, 1477-0539, 1477-0539
Online Access:Get more information
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Summary:Lewis base dependent (3 + 3) annulation of delta-acetoxy allenoates with benzofuranone, pyrazolone, and Boc-protected oxindole is reported. In the presence of catalytic DBU, oxindole, benzofuranone, and pyrazolone undergo (3 + 3) annulation with delta-acetoxy allenoates via 6-exo-dig cyclisation at room temperature (25 degrees C) to afford fused pyran scaffolds. On the other hand, by employing catalytic DMAP, the reaction between N-Boc-oxindole and delta-acetoxy allenoates goes through 6-endo-dig cyclisation, leading to distinct dihydropyrans that contain an exocyclic double bond; similar products were also obtained by using benzofuranone and pyrazolone.
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ISSN:1477-0520
1477-0539
1477-0539
DOI:10.1039/d3ob00597f