Synthesis of 2,4‐Diaryl‐1,3‐benzoxazines via FeCl3‐Catalyzed Annulation of ortho‐Hydroxyphenyl‐Substituted para‐Quinone Methides with Imidates

A strategy has been established for the synthesis of 2,4‐diaryl‐1,3‐benzoxazines via a FeCl3‐catalyzed annulation of ortho‐hydroxyphenyl‐substituted para‐quinone methides (p‐QMs) and imidates. This transformation proceeds under mild, operationally‐simple conditions in a very short time. A wide range of substrates was accessed in this facile chemical transformation, in which the cyclized products were isolated in good to excellent yields (37% to 98%). This reaction not only provides an efficient method for the construction of biologically important 2,4‐diaryl‐1,3‐benzoxazines but also greatly enriches the chemistry of p‐QMs.