Constitution of hibiscitrin. Part II

The constitution of hibiscitrin proposed in Part I as the 3-glucoside of hibiscetin is confirmed here by synthetic experiments. The O-hexamethyl hibiscetin (A) has been ethylated to (B). Using the method of nuclear oxidation a hexamethyl hibiscetin with a free hydroxyl in position 5 is now prepared and shown to be different from (A). Ethyl ethers of the isomeric 8- and 3-hydroxy compounds are also prepared. The former is different from (B) whereas the latter is identical with it. Though alkali fission of (A) does not yield the ketonic part, the ethyl ether (B) can be satisfactorily employed for this fission. The ketonic product is found to be identical with ω-ethoxy-2-hydroxy-3: 4: 6-trimethoxy-acetophenone obtained synthetically, thus confirming again the above constitution of (B) and of hibiscitrin.