boscalid

Boscalid is a broad spectrum fungicide used in agriculture to protect crops from fungal diseases. It was first marketed by BASF in 2002 using their brand name Endura. The compound is an biphenyl amide derived inhibitor of succinate dehydrogenase.

==History== Inhibition of succinate dehydrogenase, the complex II in the mitochondrial respiration chain, has been known as a fungicidal mechanism of action since the first examples were marketed in the 1960s. The first compound in this class was carboxin, which had a narrow spectrum of useful biological activity, mainly on basidiomycetes and was used as a seed treatment. Many companies made analogues with the aim of expanding the range of species controlled and boscalid was successful in doing so. == Synthesis == The first synthesis of boscalid was disclosed in patents filed by BASF in 1995. upright=1.5 The aminobiphenyl required for reaction with the acid chloride of 2-chloronicotinic acid is prepared in two steps. The first is a palladium-catalysed Suzuki reaction with 2-chloro-1-nitrobenzene and 4-chloro-phenylboronic acid, followed by hydrogenation of the nitro group. As the final product has been manufactured at the multi-tonne scale, considerable efforts have been made to improve yields.