Enantioselective Synthesis and Biological Evaluation of Sanglifehrin A and B and Analogs

SanglifehrinA and B are immunosuppressive macrocyclic natural products endowed with and differentiated by a unique spirocyclic lactam. Herein, we report an enantio-selective total synthesis and biological evaluation of sanglifehrin A and B and analogs. Access to the spirocyclic lactam was achieved through convergent assembly of a key pyranone intermediate followed by a stereo-controlled spirocyclization. The 22-membered macrocyclic core was synthesized by ring-closing metathesis in the presence of 2,6-bis(trifluoromethyl) benzeneboronic acid (BFBB). The spirocyclic lactam and macrocycle fragments were united by a Stille coupling to furnish sanglifehrinA and B. Additional sanglifehrin B analogs with variation at the C40 position were additionally prepared. Biological evaluation revealed that the 2-CF3 analog of sanglifehrin B exhibited higher anti-proliferative activity than the natural products sanglifehrin A and B in Jurkat cells. Both natural products induced higher-order homodimerization of cyclophilinA (CypA), but only sanglifehrinA promoted CypA complexation with inosine-5'-monophosphate dehydrogenase 2 (IMPDH2). The synthesis reported herein will enable further evaluation of the spirolactam and its contribution to sanglifehrin-dependent immunosuppressive activity.

Automated summary

This study presents the enantio-selective total synthesis and biological evaluation of sanglifehrin A and B and analogs. The 2-CF3 analog of sanglifehrin B exhibited higher anti-proliferative activity in Jurkat cells, while sanglifehrin A promoted CypA complexation with IMPDH2. The synthetic approach reported here will enable further investigation of the contribution of the spirolactam to sanglifehrin-dependent immunosuppressive activity.