A new ruthenium‐catalyzed cyclization of ortho‐(alkynyloxy)benzylamines to dihydro‐1,3‐benzoxazines is reported. The cyclization is thought to take place via the vinyl ruthenium carbene intermediates which are easily formed from Cp*RuCl(cod) and N2CHSiMe3. The mild reaction conditions and the efficiency of the procedure allow the easy preparation of a broad range of new 2‐vinyl‐2‐substituted 1,3‐benzoxazine derivatives. Rearrangement of an internal C(sp) in the starting material into a tetrasubstituted C(sp3) atom in the final 1,3‐benzoxazine is highly remarkable. A new addition: A new ruthenium‐catalyzed cyclization of ortho‐(alkynyloxy)benzylamines to 1,3‐benzoxazines is reported. Vinyl ruthenium carbenes are proposed as the key intermediates, and the mechanistic hypothesis supposes the first example of a nucleophilic addition of amines to vinyl ruthenium carbenes. Rearrangement of an internal C(sp) into a tetrasubstituted C(sp3) is highly remarkable. TMS=trimethylsilyl.