Multikilogram-Scale Preparation of AZD4635 via C–H Borylation and Bromination: The Corrosion of Tantalum by a Bromine/Methanol Mixture

An efficient route to AZD4635 has been developed utilizing the Suzuki–Miyaura reaction of a boronate ester prepared by C–H borylation on a multikilogram scale. Preparation of the cross-coupling partner using bromine/pyridine/methanol has highlighted the incompatibility of this reagent/solvent combination with tantalum, which is commonly used in the construction and repair of standard manufacturing vessels.