Synthesis of boscalid

Boscalid is an agricultural fungicide manufactured on a scale of thousands of tonnes per year. Its industrial synthesis begins with a Suzuki coupling between 2-chloronitrobenzene and 4-chlorophenylboronic acid.

The nitro group activates the adjacent C–Cl bond towards oxidative addition, so palladium distinguishes between the two aryl chlorides and the one on the boronic acid does not react. Reduction of the nitro group gives the 2-aminobiphenyl, which is acylated with 2-chloronicotinoyl chloride to give boscalid.