Reactions with Chlorosulfonyl Isocyanate: Formation of 2H-1,3-Benzoxazine-2-Ones

Abstract

In recent years chlorosulfonyl isocynate (CSI), an electrophilic reagent has been extensively employed in the synthesis of heterocyclic compounds. We have earlier reported on the reactions of CSI with - 2- aminobenzophenones leading to the formation of 4-aryl-2(IH)-quinazolinones¹ and with 2-hydroxy benzaldehydes, 2-hydroxyacetophenones or -benzophenones at elevated temperature, 2-hydroxyacetophenones or-benzophenones or- benzophenones at elevated temperature (100–105°) giving rise to 1,2,3- benzoxathiazine- 2, 2-dioxides². It is known that the temperature profoundly influences the course of the reaction and formation of the products in case of phenolic compounds, it was considered of interest to carry out the reaction of CSI with 2-hydroxycompounds (1a-e;6a-e) at room temperature (25–30°), to obtain 1,3-benzoxazine-20-ones which have attracted considerable attention to thier biological activity.