Synthesis of new hydroxy-2-styrylchromones

http://apps.isiknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=5&SID=V1M67gPH3IpI7j5a98j&page=1&doc=1&colname=WOSHydroxy-2-styrylchromones 5a−i were prepared by debenzylation of benzyloxy-2-styrylchromones 3a−i, which were synthesised by the Baker−Venkataraman method. The last step of this method, the cyclodehydration 5-aryl-3-hydroxy- 1-(2-hydroxyaryl)-2,4-pentadien-1-ones 2a−i, was carried out with a catalytic amount of iodine, or p-toluenesulfonic acid, in DMSO. Benzyloxy-3-cinnamoyl-2-styrylchromones 4a−f were obtained as by-products in both procedures, but the latter procedure gave benzyloxy-2- styrylchromones 3a−i in better yields. The structures of all new compounds were established by extensive NMR studies