Synthesis of 3-Substituted and 2,3-Disubstituted-4H-1,4-Benzoxazines

Two new and efficient synthetic routes towards substituted 4H-1,4-benzoxazine derivatives were reported. The first one involves the synthesis in four steps of the 4-Boc-4H-1,4-benzoxazine and its regioselective substitution on C-3 following a lithiation–electrophilic substitution sequence. The second route involves palladium-catalyzed coupling reactions between organostannanes and a vinylphosphate obtained from a benzoxazin-3-one derivative.