Straightforward Synthesis of 2-Substituted 3,4-Dihydro-2<i>H</i>-1,4-benzoxazines under Solid−Liquid Phase Transfer Catalysis Conditions

Abstract

A straightforward and efficient synthesis of 2-substituted 3,4-dihydro-2 H -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.