Unusual nicotinoylation of 4-phenyl-5,7-dihydroxycoumarin

In the present work, we report a convenient synthesis of 5- and 7-substituted-4-phenyl coumarins. contrast to previous results obtained with 4-alkylcoumarins, nicotinoylation 5,7-dihydroxy-4-phenylcoumarin nicotinoyl benzotriazole or azide selectively provides 5-O protected ester. The combination reaction followed by tosylation-denicotinoylation yields 5-hydroxy-7-tosyloxy-coumarin derivative, which may be useful in inophyllum, tetracyclic HIV reverse transcriptase inhibitor, as well its analogues.