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.We have synthesized some angular pyranocoumarins in tandem cyclization method in few steps.