Mode triketone

Birch and cowoikers fully elaborated the polyketide hypothesis and examined possible biomimetic syntheses. In one example, treatment of 7-pyrone (129) with base was found to give a mixture of resorcinols (131 dihydropinosylvin) and (132), presumably from the two modes of intramolecular al-dolization of triketone (130 equation 149). ... 

As discussed in detail in Chapter 4.2, triketones exert their herbicidal mode of action by inhibition of 4-hydroxyphenylpyruvate dioxygenase (HPPD) [6]. Triketones are not the only herbicide class that have this mode of action, and it has retrospectively been shown that apparently structurally non-related heterocyclic commercial herbicides such as isoxaflutole (7, BALANCE and MERLIN ), and the rice herbicides pyrazolate (8, SANBIRD ) and benzobicyclon (9, SHOW-ACE ) also cause these bleaching symptoms by the same mode of action. However, a common feature of these herbicides, after metabolic activation to the active metabolites (7 ) [7], (8 ) [8] and (9 ) [9] is the presence of an acidic 1,3-dicarbonyl moiety, which is also present in triketones (Fig. 4.3.2). Triketones and related her-... 

Since their discovery in the early 1980s, the triketone herbicides have been extensively studied over the last two and half decades. In view of this, it may surprise the reader that only three commercial products have appeared to date. However, as has been described, other triketone products are due to appear on the market (e.g., tembotrione), and related compounds with this mode of action (see Chapter... 

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