Synthesis of Biologically Active Angular Pyranocoumarins

Coumarins (2H-l-benzopyran-2-ones, 1) are secondary metabolites produced by plants belonging to families like leguminosae, rutaceae, umbelliferae arid compositae. There are lots of controversies regarding the exact role of coumarins in plants but it is known that they act as growth regulators, seed dormancy regulators, bacteriostats, fungistats etc.Many naturally occurring angular pyranocoumarins show interesting biological activities. Thus, alloxanthoxyletin is known to have insecticidal activity, Calophylloloide has been reported to exhibit high oral anticoagulant, antitubercular, antiinflammatoiy and antiarithritic activities.In present study, convenient methods have been described for the syntheses of angular pyranocoumarins, alloxanthoxyletin , dihydrodipetalolactone and dihydrocitrusarin A starting from toddaculine through the common precursor dihydropyranocoumarin