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The synthesis and antiallergic activity of a series of 2-hydroxy-N-1H-tetrazol-5-ylbenzamides and isomeric N-(2-hydroxyphenyl)-1H-tetrazole-5-carboxamides is described. A relationship between structure and intravenous antiallergic activity in the rat passive cutaneous anaphylaxis (PCA) test has been established using a Hansch/Free-Wilson model and used to direct studies toward potent derivatives. The contribution of physicochemical properties to activity is discussed. One member of this series, N-(3-acetyl-5-fluoro-2-hydroxyphenyl)-1H-tetrazole-5-carboxamide (3f), which was selected for further evaluation, has an ID50 value of 0.16 mg/kg po and is 130 times more potent than disodium cromoglycate (DSCG) on intravenous administration.

The properties of the product of oxidation of colupulone, having the structure assigned to cohulupone, have been examined in detail. Despite the fact that the concentration of hulupones in hops is usually less than 0.5% of the dried cones they interfere in colorimetric, spectrophotometric and conductimetric methods of hop analysis and in most methods of estimation of the isohumulones in beer. Higher values reported for the concentration may be due to the formation of artefacts. The β acids are readily oxidized to hulupones, and this conversion takes place during wort boiling, thus providing a demonstration of the contribution of the β acids to the bittering substances present in beer.

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Physical and chemical methods have been used to show that laccaic acid Al, the major pigment of stick lac, is 3-[3-(2-acetamidoethyl) -6-hydroxyphenyl] -l,2,4,7-tetrahydroxyanthraquinone-5,6-dicarboxylic acid. Exeter

Representatives of two new classes of meso-ionic heterocycles have been synthesised, the I ,2,4-thiadiazolium-3-olate (8) and the 1,2,4-thiadiazolium-3-tosylaminide (25). The reactions of 1,2,4-thiadiazoles and nucleophiles follow two general pathways : (i) reductive transformation to N-thiobenzoyl derivatives and (ii) elimination of elemental sulphur and the formation of N-benzoyl derivatives. A mechanistic rationale is proposed for the operation of pathways (i) and (ii). Earlier views on the oxidative formation of certain 1,2,4-thiadiazoles are corrected. A novel synthetic route to heterocycles containing sulphurnitrogen bonds is described. 1,2,4-Thiadiazoles are formed by oxidation of N-thiobenzoylureas and Nt hio benzoylg uanidines by bis (4met hoxyp hen yl) telluroxide.Four types of meso-ionic thiadiazoles can in principle exist as possible members of the type-A class of meso-ionic heterocycles.2 These are the conjugated mesomeric betaine derivatives of 1,2,3-thiadiazoles [(I) and (2)], 1,3,4-thiadiazoles (3), and 1,2,4-thiadiazoles (4). Meso-ionic heterocycles of the types (I), (2), and (3) have been extensively investigated.* Known representatives include the 1,2,3-thiadiazolium-4olates (1 ; X = 0), 1,2,3-thiadiazolium-5-olates (2; X = 0), 1,2,3-thiadiazolium-5-aminides (2; X = NR3), 1,2,3-thiadiazolium-5-thiolates (2; X = S ) , 1,2,3-thiadiazolium-5methylides (2; X = C Y Z ) , 1,3,4-thiadiazolium-2-0lates (3 ; X = 0), 1,3,4-thiadiazolium-2-aminides (3; X = NR3), 1,3,4-thiadiazolium-2-thiolates (3 ; X = S), and 1,3,4-thiadiazolium-2-methylides (3; X = CYZ). It is interesting to note that the pioneering investigations on the 1,3,4-thiadiazolium-2-thiolates (3; X = S) were carried out by Busch (1865Busch ( -1941, long before it was recognised that these compounds could be appropriately formulated with monocyclic meso-ionic structures.The claim to have prepared the first example of a mesoionic 1,2,4-thiadiazole (4; R' = Ph, R2 = Me, X = NH)