Synthesis of Novel 3-Acyloxy-1,3-dihydro-2H-indol-2-ones and Isomeric 4-Acyl-1,4-dihydro-3,1-benzoxazin-2-ones: Double Rearrangement of 3-Hydroxyquinoline-2,4(1H,3H)-diones

Substituted 3-hydroxyquinoline-2,4(1H,3H)-diones 3 were transformed into 3-acyloxy-1,3-dihydro-2H-indol-2-ones 4 and isomeric 4-acyl-1,4-dihydro-3,1-benzoxazin-2-ones 5. The influence of the substituents and the reaction conditions on the course of the reaction was studied. In the proposed mechanism a double rearrangement takes place; α-ketol rearrangement of 3, leading to α-hydroxy-β-diketone intermediate 8, is followed by a rearrangement to the isomeric α-ketol-esters 4 and 5.