Of note, specific entries were elaborated to enable access to defined precursors of type 42 (Scheme 2). To introduce chloro groups at the 2-and 5-position of the phenylene core, we started from 4-bromo-2,5-dichlorobenzoic acid (47). After a cross-coupling reaction at an early stage, the biaryl carboxylic acid 48 was submitted to a carbodiimide-assisted conversion with N,O-dimethylhydroxylamine to give the Weinreb amide 49. Subsequent reductive cleavage with lithium aluminum hydride furnished aldehyde 50. The following two steps comprised a reductive amination to 42q and the generation of the envisaged VHL ligand 17 (Table ).