PIDA-promoted metal-free [3 + 2] heteroannulation of ß-ketothioamides with 4-hydroxy coumarins: chemo-/regioselective access to furo[3,2-c]chromen-4-ones at room temperature.
Org Biomol Chem
; 22(21): 4326-4331, 2024 May 29.
Article
in En
| MEDLINE
| ID: mdl-38722080
ABSTRACT
Herein, we report a viable protocol to access furo[3,2-c]chromen-4-ones by engaging easily accessible 4-hydroxy coumarins as a three-atom CCO unit and thioamides as a C2 coupling partner, mediated by phenyliodine(III) diacetate (PIDA) at room temperature in a highly efficient and pot-/step-economical manner. This strategy not only avoids potential toxicity and tiresome workup conditions, but also features operational simplicity, a broad substrate scope, good functional group tolerance, high yields, easy scalability and exclusive selectivity. A mechanistic study has shown that this metal-free reaction is triggered by PIDA via activation of the ß-carbon of 4-hydroxy coumarin, followed by a nucleophilic addition/intramolecular cyclization/dethiohydration cascade. High-resolution mass spectra (HRMS) study confirms the key intermediates involved during the course of the reaction, elucidating the reaction pathways, and demonstrates the excellent regio- and chemoselectivity of this approach.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Org Biomol Chem
/
Org. biomol. chem
/
Organic & biomolecular chemistry
Journal subject:
BIOQUIMICA
/
QUIMICA
Year:
2024
Document type:
Article
Affiliation country:
India
Country of publication:
United kingdom