Ginkgetin, isolated from the leaves of the Maidenhair tree , has previously been regarded as 6 : 8-dihydroxy-4'-methoxyflavone. The dimethyl ether (11) of this substance and the isomeric 6 : 6 : 4'-trimethoxyflavone (V), as well as a number of derivatives of both compounds, have been synthesised by established methods, and their properties prove that ginkgetin can be neither 5 : 8-nor 6 : 6-dihydroxy-4'-

Clioloselectnn, n re]iiitccl S-ruv coiitrust for tlic pill blncl~ler. is atatcd to pos..cas foniiu~ii (I). I t nlq&irs to Irnvc ~l e r i~ 1ircpwerI IIV tIio roil~Ieiientiori of ioc~oisntin (11) wit~i 3 : ~-c~i-iirc~o-~-~-~igc~rosgeilic~sgiic~eto-pliciioiio (HI), nncl nltlioigli the ~~roiliict frorii this rciiction w i i H piveil atriictum (I\'), it is itow sliow~i tlint I lie oiilv inolitblc clietiiir~il iiiiliviiliinl is tho siiiiplu hrivtitiw (V), tIic Iiydrvsgut\;yl proiip being eIiiiiiiii~tci~ by ligclrolgsis rlitritig tliu i~oiiilci~aiitiori. Cl~oloselr~~trin WIIS ~~rob;ibIy tlic c a n i~~~t t~i~I (V) iii II wry iriipiiru I I~I I I~.Cliolosclcctrin, ii rcputerl .Y-r:iy ctiiitriist. for the g~ill l)liitltler, w t s first mciit.ioiic!cl 11y l'ril)rmi.* It wis stater1 to IJC t lie iotliniitetl 3-~~1ienylquititrlittc-~I-c~iirlrosylic iicitl deriviitivc (I), i t n i l II further reference to the cotnpotititl w i s rtintlc hy lIiiix,z hut since then Choloselcctiin liiis only liccri inrtitionctl Iwicfly Iiy I

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