Synthesis of 1,2,4-triazole compounds related to the fungicides flutriafol and hexaconazole
1991
Worthington, P.A.
Triazole and imidazole compounds are important both as pharmaceutical and agrochemical fungicides. It has been demonstrated that they exhibit this activity because they inhibit the 14 alpha-demethylase enzyme involved in the biosynthesis of fungal sterols. A knowledge of the mode of action of the triazoles paclobutrazol, diclobutrazol and propiconazole has made it possible to devise inhibitors of the 14 alpha-demethylase enzyme somewhat more readily, using computer graphic techniques. These techniques were used in the discovery of flutriafol, one of the first example of a triazole tertiary alcohol structure. They also assisted in identifying other triazole tertiary alcohol structures for testing as fungicides. Hexaconazole is one example of a highly active broad-spectrum fungicide. Modification of the hexaconazole structure has produced many other active fungicides, many of which can be conveniently synthesised by the addition of organometallic (e.g. lithium, magnesium, aluminium, titanium or zinc) reagents to alpha-1,2,4-triazol-1-yl ketones or alpha-haloketones. Alternatively, they can be prepared by the reaction of nucleophiles such as mercaptans, nitrogen heterocycles or organometallic (e.g. magnesium) reagents with epoxides.
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