3- pyridine agrochemicals

Bipyridines. Siace the 1960s, the most important commercial agrochemical based on pyridine has been the herbicide paraquat (20) which is made from 4,4 -bipyridine (19). The isomeric herbicide diquat (59) is made by an analogous route, but utilising 2,2 -bipyridine [366-18-7] as a precursor. 

Fluorinated heterocycles have many uses and the following are some typical examples. Trifluoromethyl pyridines are useful building blocks for agrochemicals (91MI1). Fluorinated quinolones have evoked considerable interest in the last 10 years as antibacterial agents (90MI1, 90MI2). The... 

A general procedure for acylation of 2-aryl-5(4//)-oxazolones using an acylating agent in the presence of 4-(dimethylamino)pyridine and triethylamine has been described.The resulting products are useful intermediates for agrochemicals and drugs. 

Whereas thousands of tons of pyridine and picolines are required for agrochemical, vitamin B3, and consumer product markets, lutidine and collidine derivatives are made on the 10-100 ton scale only, primarily for use as solvents and intermediates in the pharmaceutical industry. Acetone, CH2O, and ammonia are used commercially to produce 2,6-lutidine (21) over metal-promoted catalysts. Zeolites MFI [45] and BEA [26] have featured in the most recent literature. 

We have already seen how different types of catalysts can be used to arrest the hydrogenation of a triple bond at the double-bond stage. A solvent or additive can also accomplish this by competitive chemisorption on the catalyst. An example (reaction 6.42) is the hydrogenation of dehydrolinalyl acetate (46) to linalyl acetate (47), a perfumery chemical, without further hydrogenation to the unwanted dihydrolinalyl acetate (48). Compound (48) should be present in less than 2% to preserve the perfumery quality of (47). This can be accomplished by using Pd/C as catalyst with pyridine as the additive or solvent (Gilbert and Mercier, 1993). A similar application can be found in the synthesis of ethylenic diol (Baillard et al., 1988) used in agrochemicals. 

The first syntheses were developed in the 1980s by Kozo Shiokawa at Nihon Bayer Agrochem. The iminoimidazolidine was formed by reaction of the diamine with cyanogen bromide however, this product could be nitrated on the nitrogen in only poor yields (a). [ 145] Shigeru Kojima prepared imidacloprid by reaction of the diamine with dimethyl nitrocarboimidodithioate in dichloro-methane (b). [146] The best synthesis is probably the reaction of 2-chloro-5-(chloromethyl)pyridine and 2-nitroiminoimidazolidine with potassium carbonate in acetonitrile. [ 147] The reaction may be catalysed by 3-5 mole percent of caesium chloride (c). [148]... 

The pyridine ring is ubiquitous in compounds of pharmaceutical and agrochemical interest. Six-membered heterocycles such as pyridines, quinolines, isoquinolines, and acridines can also be obtained by the reactions of the pyrylium salts with ammonia derivatives. 

Heterocyclic compounds which contain a pyridine ring are frequently found in natural products. Accordingly, they are of special interest in pharmaceutical, agrochemical, and medicinal chemistry [117]. Also, a number of pyridine derivatives have been used in material chemistry [118]. Bipyridine groups are... 

Useful precursors for agrochemicals were obtained by either single or double alkoxycarbonylation of a dichloropyridine 4.65 (Scheme 4.27). Either product, 4.66 or 4.67, could be obtained by the choice of the reaction temperature, on a 120 g scale. For single carbonylation, the expected selectivity (see Chapter 2, Section 2.1.4) for greater reactivity a to the pyridine nitrogen giving ester 4.67 was found. 

Our experience has not only shown the excellent utility of 3-tfm-pyridine building blocks. In addition, the role of this moiety as a carrier to improve transport of agrochemicals was confirmed, both by the theoretical approach of quantitative structure-acitvity relationships and by actual experimental results. Some highlights of this research form the first part of this paper. 

To further study the utility of 3-tfm-pyridines in agrochemicals, we have focused our research to compounds in which the 3-tfm-pyridine is bonded to the rest of the molecular structure via sulfur. One chemical class investigated was sulfonylurea herbicides, and SL-160, the second 3-tfm-pyridine herbicide developed by ISK, was found (4). SL-160 is different from compounds of Figure 1 in that... 

Background of the Invention. Although the key intermediate required to produce fluazifop butyl, ch1orf1uazuron and fluazinam is 2,5-CTF (8), some other (chloro-)tfm-pyridines occur as byproducts in the manufacturing process (simultaneous vapor-phase chlorination and fluorination of 3-picoline) developed by ISK, as shown in Figure 3. 2,3-CTF and 2,6,3-DCTF can be reduced to TF, which can then be re-fed to the reaction. However, since direct separation and effective application of the byproducts is undoubtedly preferable with respect to cost performance, we sought an appropriate agrochemical mother-skeleton to which such 3-tfm-pyridine intermediates can be introduced. 

The development of fluazifop butyl and ch1orf1uazuron has established the utility of tfm-pyridines as building blocks for agrochemicals. In addition, structure-activity... 

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