1 h nmr cdcl 3 u03b4 3 82 3 h s 3 96 3 h s 4 03 3 h s 6 34 1 h s 7 45 7 48 3 h m 7 67 2 h d j 9 3 hz 8 06 2 h d j 15 5 hz 8 33 2 h d j 15 5 hz ir kbr cm u2212 1 3419 1608 ms m z 315 mh a mixture of chalcone 1 7 2 g 23 mmol and iodine 200 mg in dmso 25 ml was refluxed for 2 h and then carefully poured onto crushed ice 200 g the precipitate was filtered and washed with 20 na 2 so 3 purification by flash column chromatography sio 2 hexane etoac 3 1 yielded 6 3 g 87 of flavone 2 and 0 8 g 2 5 of recovered chalcone 1 mp 146 147 u00b0 c lit 164 165 u00b0 c 1 h nmr dmso d 6 u03b4 3 93 3 h s 3 97 3 h s 3 99 3 h s 6 72 1 h s 6 83 1 h s 7 50 3 h m 7 88 2 h d j 8 7 hz ir kbr cm u2212 1 1633 ms m z 313 mh a solution of flavone 2 0 20 g 0 64 mmol in 47 hbr 5 ml and glacial acetic acid 10 ml was refluxed for 2 h and then carefully poured onto crushed ice 200 g the resulting yellow precipitate was filtered and collected.