Cyanoacetamide, control

Variations include the use of yne-ones, when conjugate addition of the cyanoacetamide controls the regiochemistry of reaction, and 3-alkoxy-enones (i.e. the enol ethers of 1,3-diketones) when comparably, the initial Michael-type... 

More general processes rely on variations of the Guareschi-Thorpe reaction [14] where condensations between 1,3-dicarbonyls and cyanoacetamide yield functionalized monocyclic 2(lff)-pyridones (a and b. Scheme 2) [15, 16]. Unless the carbonyls are sufficiently different in reactivity, the reaction suffers from poor regioselectivity. The use of 3-alkoxy or 3-amino enones instead of 1,3-dicarbonyls has proven to be a versatile and reliable synthetic methodology where the 1,4-addition controls the regioselective outcome (c and d. Scheme 2) [17-19]. 

By reaction of ethyl acetoacetate with cyanoacetamides, pyridones are easily accessible. By selection of suitable substituents in the diazo components, shade and fastness properties and build up can be controlled (e.g., 39-42 and Disperse Yellow 211). 

Within the past ten years, the market introduction of several new types of fungicides has significantly improved the prospects of controlling the Oomycetes. They belong to five different chemical classes the carbamates, the isoxazoles, the cyanoacetamide oximes, the etheyl phosphonates, and the acylalanines and related compounds. The chemical structures of those chemicals that have reached the commercial level are shown in Figures 3-5 (29, revised). Trade names, formulations and first reports are summarized in Table II (29, revised). The biological characteristics of these new fungicides and their impact on disease control have been reviewed by several authors (10, 16, 27, 28, 29, 33). 

A similar approach has been used for the synthesis of 3-lH-pyrazolo[3,4-fc]pyridyl-indole ° and 2-aminochromene libraries, the latter being performed solvent free using a clay as a support and base. In addition, a library of over 100 derivatized substituted 2-pyridones (21 x 5 members) has been prepared by the reaction of 1,3-cyclohexane-diones, dimethylformamide dimethylacetal, and various cyanoacetamides (Scheme 4.10). The outcome of the reaction could be controlled to furnish different products by changing the basicity of the medium to involve either the amide or nitrile functionality of the cyanoacetamide substrate during the 2-pyridone ring-formation step. 

Retention-aid chemicals may be added, as well as defoamers (e.g. fatty-acid compounds), pitch-control agents, optical brighteners (usually stilbene derivatives) and, in some cases, fibre deflocculants. Different slimicides are also added to the stock for microbe control. A number of chemicals can be used for this purpose, such as 1,5-pentanediol, 2,2-dibromo-3-nit-rile propionamide, 2,2-dibromo-2-cyanoacetamide, 5-chloro-2-methyl-4-isothiazolin-3-one + 2-methyl-4-iso-thiazolin-3-one (Kathon CG) or glutaraldehyde. 

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