Lithiation ofN-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 a-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.