Ames and Davey:368. cycloHexane-1 : 3-diones. Part I V. * The Synthesis of Further T erp h en y 1 Derivatives. By G. R. AMES and W. DAVEY.3 : 4-Di-, 3 : 4 : 3'-tri-, and 3 : 4 : 3' : 5'-tetramethoxy-P-terphenyl have been prepared from 5-(3 : 4-dimethoxyphenyl)-2-phenylcyclohexane-1 : 3dione. 4 : 5-Diphenylcyclohexane-1 : 3-dione has been converted into 3' : 5'-dihydroxy-and 3' : 5'-dimethoxy-o-terphenyl. Syntheses of 4' : 6'dihydroxy-m-terphenyl and of 2' : 4'-and 4' : 6'-dimethoxy-un-terphenyl are also described.IN Part I1 of this series it was shown that dehydrogenation of compounds derived from 2 : 5-diphenylcyclohexane-1 : 3-dione afforded a new and convenient route to a number of 9-terphenyls substituted in the central ring. This method has now been applied to the synthesis of P-terphenyls having methoxyl substituents in two rings, and also to o-and m-terphenyl derivatives Polymethoxy-p-ter$henyls.-The synthesis of terphenyl derivatives from 5-(3 : 4-dimethoxyphenyl) -2-phenylcyclohexane-1 : 3-dione (111) was examined. The dione was conveniently prepared by Michael addition of ethyl y-phenylacetoactate to ethyl 3 : 4-dimethoxycinnamate (I), followed by hydrolysis of the dione-ester (11), and was converted by diazomethane into the enol ether (IV). Dehydrogenation with sulphur, followed by treatment with dimethyl sulphate, then afforded 3 : 4 : 3' : 5'-tetramethoxy-$-terphenyl (V) in 35% yield.The alternative route to the dione-ester (11), namely addition of diethyl malonate to the unsaturated ketone (VI), was not examined as the latter could only be prepared in low yield and with difficulty.The enol ether (IV) was reduced with lithium aluminium hydride and then dehydrogenated with sulphur, to give 3 : 4-dimethoxy-(VII; R = H) (10%) and 3 : 4-dimethoxy-3'-hydroxy-@-terphenyl (VII; R = OH) (17%). The latter product was converted into the triether (VII; R = OMe) by treatment with dimethyl sulphate and alkali. The formation of the diether (VII; R = H) in the above reaction is analogous to that of 9-terphenyl when the diphenyl enol ether (VIII) was reduced and dehydrogenated in the same way.l *

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The methods used for the assay of lipoxidase have been compared. The pH profile of the enzyme, as measured by two of the methods, was found to be considerably altered by changes in the ionic strength of the readon medium.