Molecular design and synthesis of coumarin by indexing

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1)Development of a novel synthetic method of salicylaldehyde(1)Claisen rearrangement of aryl propargyl ether in the presence of CsF afforded exclusively an arylfuran, which was converted to salicylaldehyde(1)by successive treatment with OsO_4 NaIO_4 and aq. NaHCO_3 in good yield. oxidation oy the furan ring with ozone was more convenient and effective.2)Convenient synthesis of coumarin(2)by reaction of with wittig reagent Reaction of 1 with Ph_3 P=CHCOOEt in diethylaniline under reflux gave coumarin(2)in a high yield. Tae methoxy substituent at C_4 on 1 facilitated the formation of coumarin ring in comparison with the methoxy group at other positions.3)Structural elucidation of naturally occurring coumarins by syntheses In connection with synthetic studies on Reisch's coumarin, coumarins(3 and 4)were synthesized by utilizing novel methods mentioned above. Moreover, the coumarin isolated from a Compositae plant by Dopke was synthetically proven to be 7, 8-dimethoxycoumarin, not 5, 8-dimethoxycoumarin.