Abstract Efficient synthesis of N,O‐heterocyclic tetra‐substituted trifluoromethyl‐3,1‐benzoxazines via a transition‐metal‐catalyzed decarboxylative intramolecular cyclization was achieved. The decarboxylation of N‐benzoyl trifluoromethyl‐benzoxazinones generated the amide oxygen nucleophile, allowing a selective internal C1‐attack on Pd‐ or Cu‐coordinated zwitterions, affording medicinally attractive tetra‐substituted vinyl‐ or ethynyl‐trifluoromethyl‐3,1‐benzoxazines. This protocol can be applied to the synthesis of perfluoroalkyl‐ and non‐fluorinated 3,1‐benzoxazines.
