Access to Highly Strained Tricyclic Ketals Derived from Coumarins

Synthesis of highly strained fused substituted dihydrobenzopyran cyclopropyl lactones derived from coumarin carboxylates are reported. The substrate scope tolerates a variety of 6- and 8-substituents on the coumarin ring. Substitution at the 5- or 7-position is resistant to tricyclic lactone formati...

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Bibliographic Details
Published in:Journal of organic chemistry 2022-03, Vol.87 (6), p.4476-4482
Main Authors: Jonnalagadda, Sravan K, Huwaimel, Bader I, Jonnalagadda, Shirisha, Garrison, Jered C, Trippier, Paul C
Format: Article
Language:English
Subjects:
Coumarins
Ethers
Lactones
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Summary:Synthesis of highly strained fused substituted dihydrobenzopyran cyclopropyl lactones derived from coumarin carboxylates are reported. The substrate scope tolerates a variety of 6- and 8-substituents on the coumarin ring. Substitution at the 5- or 7-position is resistant to tricyclic lactone formation except with 7-methyl substitution. Benzamide-containing coumarins afford the tricyclic ketal. A plausible mechanism is proposed for the formation of the fused lactone: intramolecular rearrangement of trans cyclopropyl methyl ketones with phenolic acetate via the formation of a hemiacetal.
ISSN:0022-3263
1520-6904
DOI:10.1021/acs.joc.2c00018