Chiral Isoxazole‐Containing Triarylmethanes Through Enantioselective Nucleophilic Addition of 5‐Aminoisoxazoles to Ortho‐Quinone Methides and Their Antifungal Evaluation

Abstract Isoxazole derivatives are known to exhibit a broad spectrum of biological activities including antimicrobial, antitumor, antitubercular, analgesic, anti‐inflammatory, antidepressant, and anticonvulsant activities. They are also frequently used as agrochemicals. In this report, we disclose an enantioselective nucleophilic addition of 5‐aminoisoxazoles to ortho ‐quinone methides catalyzed by a chiral phosphoric acid. This transformation allowed the synthesis of a range of enantioenriched isoxazole‐containing triarylmethanes. The absolute configuration of one product was determined by an X‐ray crystal structural analysis. A plausible mechanism was proposed. Moreover, several products were evaluated in antifungal activity against plant pathogenic fungi R. solani and two of them displayed promising activities.