Lithiation of N‐protected‐dihydro‐1,4‐benzoxaziness

Lithiation of N‐protected‐2,3‐dihydro‐1,4‐benzoxazines is described. Lithiation of N‐(tert‐butoxycarbonyl)‐2,3‐dihydro‐1,4‐benzoxazine ( 1 ) with BuLi/TMEDA occurred in the α‐position to nitrogen on the heterocyclic ring, leading to the unexpected ring‐opened product 3 . On the other hand, lithiation of N‐methyl‐2,3‐dihydro‐1,4‐benzoxazine ( 4 ) took place at the oxygen‐adjacent ortho‐position of the aromatic ring.