Reducing Limitation in Probe Design: The Development of a Diazirine-Compatible Suzuki-Miyaura Cross Coupling Reaction.

Access to high quality photoaffinity probe molecules is often constrained by synthetic limitations related to diazirine installation. A survey of recently published photoaffinity probe syntheses identified the Suzuki-Miyaura (S-M) coupling reaction, ubiquitous in drug discovery, as being underutilized to incorporate diazirines. To test whether advances in modern cross-coupling catalysis might enable efficient S-M couplings tolerant of the diazirine moiety, a fragment-based screening approach was employed. A model S-M coupling reaction was screened under various conditions in the presence of an aromatic diazirine fragment. This screen identified reaction conditions that gave good yields of S-M coupling product while minimally perturbing the diazirine reporter fragment. These conditions were found to be highly scalable and exhibited broad scope when applied to a chemistry informer library of 24 pharmaceutically relevant aryl boron pinacol esters. Furthermore, these conditions were used to synthesize a known diazirine-containing probe molecule with improved synthetic efficiency.