Research Activities and Patent Situation

This can be attributed to the discovery of the latest generation compounds with a substantially broader biological spectrum. More than 15 companies, including most major players and also many smaller competitors, have been involved in these efforts. 

Although this class of molecules bears several striking structural similarities, the actual strategy for a large-scale synthesis depends on the specific heterocydes or aromatics involved, on their substitution pattern, and on the commercial availability of suitable precursors. 

In both examples the heterocyclic carboxylic acid has been activated as the chloride to be combined with the aniline in a straightforward converging synthesis. 

For penthiopyrad (10) a laboratory-scale synthesis has been published in which the branched alkyl residue on the thiophene ring was generated from an acetyl group by addition of methylmagnesiumbromide and subsequent reduction by triethylsilane [18]. 

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