SYNTHETIC COMMUNICATIONS, cilt.38, ss.914-927, 2008 (SCI İndekslerine Giren Dergi)
We have obtained dihydrofurans 3a-j in the radical cyclization of 4-hydroxycoumarin 1a and 2-hydroxy-1,4-naphtoquinone 1b with electron rich alkenes 2a-i by manganese(III) acetate. Methods A and B, which have different molar ratios were studied comparatively in these reactions, and we observed that method B (molar ratio 2:1:3) gave the best results. Treatment of 4-hydroxycoumarin 1a and electron rich alkenes 2a-e gave 2,3-dihydro-4H-furo[3,2-c]chromen-4-ones 3a-e in 36-86% yields by the method B. Under the same conditions, the reactions of 2-hydroxy-1,4-naphtaquinone 1b with conjugated alkenes 2b and 2f-i afforded 2,3-dihydronaphtho[2,3-b]furan-4,9-diones 3f-j in an excellent yields.