An unprecedented simple pyrrolidine catalyzed [4 + 1] annulation reaction of ynals with N-protected-2-aminophenols is reported. The utilization of the unique property and reactivity of the C=C triple bond in ynals leads to two consecutive conjugate addition reactions at the same β-position with pyrrolidine via iminium activation. The powerful cascade process affords a new alternative approach to biologically and synthetically important benzoxazoles in high yields (83-95%).
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry