3-Bromo-4-hydroxycoumarin (11) has previously been prepared in this Laboratory by the reaction of bromine with a suspension of 4-hydroxycoumarin (I) in chloroform. 2 This procedure was found to be tedious and the manipulation difficult for large scale synthesis. We have devised a modification of the original procedure which, in addition to being more convenient, gave a nearly quantitative yield of 11. free isothiourea derivative (IV) was ...
