Straightforward synthesis of 2-substituted 3,4-dihydro-2H-1,4-benzoxazines under solid-liquid phase transfer catalysis conditions

A straightforward and efficient synthesis of 2-substituted 3,4-dihydro-2H-1,4-benzoxazines 6-9 has been carried out in excellent overall yields through the ring opening of epoxides 1 with arylsulfonamides 2 and 3, followed by cyclization of the hydroysulfonamides 4 and 5 thus obtained. Both steps are carried out under solid-liquid phase transfer catalysis (SL-PTC) conditions using potassium carbonate and sodium hydroxide as bases. The procedure is feasible for the synthesis of non-racemic 2-substituted benzoxazines.