REARRANGEMENT OF SUBSTITUTED 1,3-BENZOXAZINES INTO XANTHENE-TYPE COMPOUNDS

Abstract

The rearrangement patterns of new 1,3-benzoxazines derivatives obtained by condensation of substituted salicylamides with cyclic ketones under the influence of Vilsmeier-Haack reagent has been studied. The influence of angel strain in a 4-membered spirocycle prevents the rearrangement of spiro [1,3-benzoxazine-2,1'-cyclobutan]-4(3H)-one under the action of a formylating agent. 1,3-Benzoxazines derivatives with ring sizes from 5- to 8-membered under the action of a formylating agent have formed formylxanthene derivative. Their formation reaction rate depends on the presence of electronegativity substituents at positions C-6 and C-8 of the aromatic cycle, as well as in the spiroring. In this work, we presented an effective method for the synthesis of formyl derivatives of xanthenes based on readily available salicylamide. It was found that (spiro[1,3-benzoxazine-2,1'-cyclobutan]-4(3H)-one) does not rearrange even under prolonged heating due to the spirocycle strain. The presence of bromine or iodine atoms at positions C-6 and C-8 of the aromatic cycle of 1,3-benzoxazines makes the reaction more difficult, which requires more harsh synthesis conditions.