Solution-phase parallel synthesis of Hsp90 inhibitors.

As part of an oncology chemistry program directed toward discovery of orally bioavailable inhibitors of the 90 kDa heat shock protein (Hsp90), several solution-phase libraries were designed and prepared. A 2 × 89 library of racemic resorcinol amides was prepared affording 131 purified compounds. After evaluation in a binding assay, followed by an AKT-Luminex cellular assay, three potent analogs had functional activity between 0.1 and 0.3 μM. Resolution by preparative chiral SFC chromatography led to (+)-15, (+)-16, and (+)-17 having functional IC50 = 27, 43, and 190 nM, respectively. (+)-15 exhibited high clearance in human hepatocytes driven primarily by glucuronidation as confirmed by metabolite identification. A second 8 × 14 exploratory library was designed to investigate heterocyclic replacements of the resorcinol ring. The second library highlights the use of the (−)-sparteine-mediated enantioselective Pd-catalyzed α-arylation of N-Boc-pyrrolidine to prepare chiral 2-arylpyrrolidines in parallel.