P-Triketone

Leptospermone (34) Nitisinone (35) P Triketone Hereditary tyrosinemia type 1... 

Dayan EE, Duke SO, Sauldubois A, Singh N, McCurdy C, Cantrell CL, -Hydroxyphenylpyruvate dioxygenase is a target site for P-triketones from Lep-tospermum scoparium Phytochemistry, 2007. 

Other uncommon natural derivatives are 2-acylcyclohexane-l,3-diones or p-triketones, typical of hops (Humulus lupulus, Cannabinaceae). The (3-acids from hop belong to this class of chemicals and are by-products of hop processing for brewing. The fraction containing these products has been examined in a choice bioassay for its effect on the feeding behavior... 

Figure 3. Effect of the p-triketone (-)-usnic acid (circles), the benzoquinone sorgoleone (triangles) and the commercial herbicide sulcotrione (squares) on the activity of p-hydroxyphenylpyruvate dioxygenase. The dotted line represents 50% inhibition of enzyme activity.

Abstract All plants produce compounds that are phytotoxic to another plant species at some concentration. In some cases, these compounds function, at least in part, in plant/plant interactions, where a phytotoxin donor plant adversely affects a target plant, resulting in an advantage for the donor plant. This review discusses how such an allelochemical role of a phytotoxin can be proven and provides examples of some of the more studied phytochemicals that have been implicated in allelopathy. These include artemisinin, cineoles, P-triketones, catechin, sorgoleone, juglone and related quinones, rice allelochemicals, benzoxazinoids, common phenolic acids, l-DOPA, and m-tyrosine. Mechanisms of avoiding autotoxicity in the donor species are also discussed. 

Dose-response curves against the enzyme activity of HPPD demonstrated that grandiflorone was the most active compound in the essential oil (Fig. 2). While leptospermone was less active than grandiflorone, it is by far the most abundant P-triketone in the oil. Therefore, most of the activity against HPPD can be attributed to... 

Dayan, F.E. et al. (2007)p-Hydroxyphenylpyru-vate dioxygenase is a herbicidal target site for P-triketones from Leptospermum scoparium. Phytochemistry 68, 2004-2014... 

We investigated an interaction of 2-acyl( clohexane-l,3-diones la-c containing a perfluoroalkylated side chain with o-phenylenediamine. A direct reaction of the latter with o-phenylenediamine produees a mixture of acid cleavage products, as reported for their aeyelie analogues [7], As an alternative approach to the synthesis of perfluoroalkylated dibenzo[b,e][l,4]diazepinones, an interaction of enol ethers of 2-perfluoroalkanoylcyclohexane-l,3-diones la- c with o-phenylenediamine is proposed, beeause of an advanced reactivity of enol ethers to nucleophilic reagents versus the initial cyclic P,P -triketones [8],... 

PurpurogaHin (5), a red-brown to black mordant dye, forms from electrolytic and other mild oxidations of pyrogaHol (1). The reaction is beHeved to proceed through 3-hydroxy-(9-benzoquinone (2) and 3-hydroxy-6-(3,4,5-trihydroxyphenyl)-(9-benzoquinone (3). The last, in the form of its tautomeric triketonic stmcture, represents the vinylogue of a P-diketone. Acid hydrolysis leads to the formation of (4), foHowed by cyclization and loss of formic acid... 

As in 10-104, a ketone attacks with its second most acidic position if 2 mol of base are used. Thus, P-diketones have been converted to l,3,5-triketones. ° ... 

Mit Aluminiumchlorid in Gegenwart von Wasser wurde Benzoin und COa gebildet. Analoge Ergebnisse wurden mit p-Methoxyphenyl-phenyl-triketon erhalten. 

The enzyme p-hydroxyphenylpyruvate dioxygenase is involved in the conversion of p-hydroxyphenylpyruvate into homogentisate, a key step in plastoquinone biosynthesis. Inhibition of this enzyme has an indirect effect on carotenoid biosynthesis as plastoquinone is a co-factor of the enzyme phytoene desaturase. The new maize herbicide isoxaflutole and the triketone herbicides such as sulcotrione (Figure 2.7), inhibit p-hydroxyphenylpyruvate dioxygenase and this leads to the onset of bleaching in susceptible weeds and ultimately plant death.4... 

On the pages which follow, general methods are illustrated for the synthesis of a wide variety of classes of organic compounds including acyl isocyanates (from amides and oxalyl chloride p. 16), epoxides (from reductive coupling of aromatic aldehydes by hexamethylphosphorous triamide p. 31), a-fluoro acids (from 1-alkenes p. 37), 0-lactams (from olefins and chlorosulfonyl isocyanate p. 51), 1 y3,5-triketones (from dianions of 1,3-diketones and esters p. 57), sulfinate esters (from disulfides, alcohols, and lead tetraacetate p. 62), carboxylic acids (from carbonylation of alcohols or olefins via carbonium-ion intermediates p. 72), sulfoxides (from sulfides and sodium periodate p. 78), carbazoles... 

Heating a solution of the triketone 1 in DME containing a catalytic amount of p-TsOH under reflux for 48 hours results in quantitative isomerisation to 2. Treatment of a THF solution of 1 with t-BuOK/t-BuOH at room temperature for 16 hours, on the other hand, gives a 78% yield of the diketone 3. 

Several l,6,6aA4-trithiapentalenes have been obtained by reacting / ,<5-triketones with phosphorus pentasulfide as indicated in equation (13) (7iAHC(i3)i6i,p. 182,71BSF4418). 

Dehydration of the optically active bicyclic ketols In refluxing benzene with a little p-toluenesulfonic acid could readily be effected without loss of optical purity.5 It has been shown by a research group at Schering A. G., Berlin, Germany that the triketone can be converted directly to the optically active enedione with 0.5 eq. of (S)-(-)-proline and 0.25 eq. of 1 N aqueous HC104 in refluxing acetonitrile.11... 

A portion of 1.56 g of the crude crystalline product is broken up in a small amount of ether on a coarse sintered funnel. Removal of this ether by suction gives 1.11 g of a colourless crystalline product (70.2% yield based on the triketone), m.p. 64-65.5 °C, [a]jj5 +356° (c0.99 in C6H6), u.v. 233nm (e 11 540). This represents a chemically pure sample of 97 per cent purity. Recrystallisation from ether gives optically pure (+ )-(7aS)-7,7a-dihydro-7a-methyl-1,5(6H)-indandione, m.p. 66-66.5 °C, [a]g5 +367° (c 1.0 in C6H6) (1). 

Base catalysis is not required for conjugate addition. If the nucleophile is sufficiently enolized under the reaction conditions then the enol form is perfectly able to attack the unsaturated carbonyl compound. Enols are neutral and thus soft nucleophiles favouring conjugate attack, and p-dicarbonyl compounds are enolized to a significant extent (Chapter 21). Under acidic conditions there can be absolutely no base present but conjugate addition proceeds very efficiently. In this way methyl vinyl ketone (butenone) reacts with the cyclic P-diketone promoted by acetic acid to form a quaternary centre. The yield is excellent and the triketone product is an important intermediate in steroid synthesis as you will see later in this chapter. 

The conjugate addition of dithiols to hexa-l,4-diyn-3-ones yields p,P -bis-l,3-dithiane ketones, masked 1,3,5-triketones, which have been converted into dihydro- and tetrahydro-pyrans <03OLl 147>. 

L.G. Freitas, C.W. Gotz, M. Ruff, H.P. Singer, S.R. Muller, Quantification of the new triketone herbicides, sulcotrione and mesotrione, and other important herbicides and metabolites, at the ng/l level in surface waters using LC-MS-MS, J. Chromatogr. A, 1028(2004)277. 

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