Vitamin B1-catalyzed intramolecular ring-opening cyclization of cyclopropanes to access benzannulated seven-membered O-heterocycles

Benzannulated seven-membered O -heterocycles, an important class of pharmaceutical scaffolds, currently lack efficient and mild synthetic methods. In this study, we utilized vitamin B 1 as a green catalyst to mediate the ring-opening of cyclopropanes, successfully constructing benzannulated seven-membered O -heterocycles. This method offers several advantages aligned with green chemistry principles, including the absence of metal catalysts, high atom economy, mild reaction conditions, and the use of water as a partial reaction solvent. Furthermore, a broad substrate scope, excellent yields, gram-scale synthesis, and subsequent derivatization studies validated its efficiency. Notably, the synthesized compounds demonstrated promising activity against fluconazole-resistant fungal strains, suggesting potential for the development of novel antifungal agents. Using vitamin B 1 as a green organocatalyst, this work achieves the efficient intramolecular ring-opening cyclization of cyclopropanes, providing rapid access to benzannulated seven-membered O -heterocycles with promising antifungal activity.