Convenient route to 2H-furo[3,2-c]quinolin-4-one framework using Mn(III)-based oxidative radical cyclization

Abstract

The oxidation of a mixture of 1,1-disubstituted ethenes 1 with 4-hydroxy-2-quinolinone derivatives 2 with manganese(III) acetate in boiling glacial acetic acid was investigated. The reaction of 3-substituted quinolinones 2 gave 9b-hydroxy-3,3a,5,9b-tetrahydro-2H-furo[3,2-c]quinolin-4-ones 3 and 3-(2,2-diarylethenyl)quinoline-2,4-diones 4 in moderate to good yields. On the other hand, 3,5-dihydro-2H-furo[3,2-c]quinolin-4-ones 5 were mainly produced during the reaction of quinolinones 2 having no substituent at the 3-position. The reaction pathway and the application of the reaction were discussed.