A fresh method for building up furan rings on to coumarin and flavone compounds has been studied. Starting with umbelliferone, 4-methyl-umbelliferone and 3-methoxy-7-hydroxy-flavone the corresponding angular α-methyl-dihydrofuran derivatives have been obtained. The 8-allyl compounds are first prepared and these are subjected successively to treatment with mercuric chloride, iodine in potassium iodide solution and sodium in alcohol.

By the action of aluminium chloride on karanjin using nitrobenzene as solvent, smooth conversion into karanjonol could be effected. When benzene is used instead, besides demethylation a molecule of benzene adds on to yield α-phenyl-α: β-dihydro-karanjonol. Similar addition takes place in the case of toluene also. That the double-bond of the furan ring is involved in this reaction has been established by studying the behaviour of a few similar flavone compounds under the same conditions. It has been incidentally shown that a methyl ether group in the 3-position is readily affected in nitrobenzene solution whereas in the 7-position it is stable and the preparation of 7-methoxy-flavonol is easily carried out by demethylation of 3: 7-dimethoxy-flavone.

Angelicin and psoralen combine with benzene in the presence of aluminium chloride to form 8 or 6-α: β-diphenyl-ethylumbelliferone. Two molecules of benzene add on and the furan ring is opened out. That the coumarin ring is not involved and that the furan ring is the active centre are confirmed by the following observations: (1) Coumarin and 6-nitrocoumarin are unaffected; (2) umbelliferone and 4-methyl-umbelliferone methyl ether undergo simple demethylation; (3) coumarone undergoes polymerisation too vigorously to condense with benzene; (4) coumarilic acid undergoes addition with one molecule of benzene smoothly. Coumaric acid resembles coumarilic acid in regard to this reaction (addition) and differs from coumarin.

A simple procedure employing fish is described for determining the toxicity of chemical compounds. The ‘turning-point’ is taken as the criterion of toxic effect and the toxicity is expressed in terms of fish units that of rotenone being arbitrarily fixed as 1000. A few organic compounds belonging to the group pyronofurans have been studied.

Claisen migrations of the allyl ether of 4∶7-dimethyl-5-hydroxy-coumarin gives rise to three isomeric compounds depending upon the conditions, (I) 6-allyl-5-hydroxy-4∶7-dimethyl coumarin (high yield), (II) the corresponding chroman (high yield), and (III) 8-allyl-5-hydroxy-4∶7-dimethyl coumarin (low yield). (II) has been shown to be a chroman by comparison with the corresponding methyl coumaran obtained by authentic methods from (I). The acetate of the above coumarin undergoes Fries reaction to give the 6-acetyl compound. Claisen migrations of the allyl ether of 7-hydroxy-5-methyl-coumarin yields only the 8-allyl-derivative. The difference in the behaviour of the derivatives of 5- and 7-hydroxy coumarins and the special conditions of the chroman and coumaran ring closure ofo-allyl phenols are discussed.