Triazole fungicides structure

Silylmethyltriazoles represent a new, highly active class of triazole fungicides, whose success in a wide variety of crops and climatic conditions confirms the utility of organosilicon compounds as agrichemicals. This paper describes their discovery, synthesis, and structure-activity relationships. Based on the results of worldwide field evaluations, some of which are presented, a member of this class, DPX-H6573, is being developed as a broad spectrum foliar fungicide. 

The triazole fungicides of general structure 64 such as hexaconazole 65 and flutriafol 66 are a rare case of human and plant medicine using similar compounds. They were initially used as racemates but it was soon essential to discover the active enantiomers. Conventional resolution by crystallisation of diastereomeric derivatives proved difficult. 

In addition to the trifluoromethylphenyl sterol biosynthesis inhibitors discussed in Section 2.1.1.3, a number of fluorine phenyl-containing azoles were introduced in the years 1984 through 1993. Though these molecules share some common structural features, such as the triazole heterocycle and a 4-fluorophenyl ring in at least three of the four fungicides shown below, each also has unique chemical features. For instance, in the case of flusilazole (Punch , Nustar , Triumph , Olymp ) [164], a silicon atom is present. This represented that first time silicon... 

Also, triazoles (triadimefon, penconazole, propiconazole, and myclo-butanyl structures are reported in Fig. 9.1) are fungicides widely employed in viticulture to control powdery mildew, molds, and other fungal pathogens. These compounds are classified as acutely toxic. They may affect liver functionality, decrease kidney weights, alter urinary bladder structure, and have acute effects on the central nervous system (Briggs, 1992). Due to their persistence, they may be present in fruit juices and wines. The Italian law fixed their LODs in wine between 100 and 500pg/kg. 

Triazoles are similar to triazines in that they also contain three nitrogen atoms in their ring structures, though they have only two carbon atoms in the ring structure. Amitrole and triadimefon are commonly used triazoles. Different groups of atoms that branch off the central ring structure determine the activity of the compound. The triazole compounds are systemic fungicides that inhibit the s)mthesis of a form of vitamin D. Most triazole compounds are stable in water. 

Paclobutrazol is a triazole plant growth retardant which also has fungicidal properties [1]. It is an inhibitor of cytochrome P-450 dependant enzymes such as ent-kaurene oxidase and sterol 14a-methyl-demethylase [1]. The fungicidal activity of azole compounds is believed to result from the inhibition of sterol 14a-demethylation. This causes an accumulation of 14a-methylsterols and loss of ergosterol which may have adverse effects on membrane properties [2]. However, there is evidence for other essential requirements for sterol In cell proliferation in addition to a membrane structural role [3-6].For example, in yeast mutants traces of ergosterol stimulate phospholipid formation [7] and protein kinase activity [8]. This report describes the effects of paclobutrazol on the sterol and phospholipid compositions of membranes from plant and yeast cultures. 

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