Metal- and solvent-free domino reaction of 2-isocyanophenol esters to benzoxazines: long-range 1,5-acyl migration on 1,4-diazabutatriene

The first example of intramolecular nucleophilic addition of 1,4-diazabutatriene to ester is disclosed. This approach provides a facile and versatile synthesis for functionalized 2