Synthesis of α-Heteroaryl Propionic Esters by Palladium-Catalyzed α-Heteroarylation of Silyl Ketene Acetals

A practical and efficient synthesis of α-heteroaryl propionic esters is developed by employing palladium-catalyzed α-heteroarylation of silyl ketene acetals, forming a wide variety of α-heteroaryl propionic esters with various substituents and functionalities in high yields. The success of this transformation is credited to the development of the bulky P,P═O ligand. The method has provided an efficient synthesis of α-heteroaryl propionic acids.

Discovery of a Potent and Orally Bioavailable Cyclophilin Inhibitor Derived from the Sanglifehrin Macrocycle

Cyclophilins are a family of peptidyl-prolyl isomerases that are implicated in a wide range of diseases including hepatitis C. Our aim was to discover through total synthesis an orally bioavailable, non-immunosuppressive cyclophilin (Cyp) inhibitor with potent anti-hepatitis C virus (HCV) activity that could serve as part of an all oral antiviral combination therapy. An initial lead 2 derived from the sanglifehrin A macrocycle was optimized using structure based design to produce a potent and orally bioavailable inhibitor 3. The macrocycle ring size was reduced by one atom, and an internal hydrogen bond drove improved permeability and drug-like properties. 3 demonstrates potent Cyp inhibition ( K_d = 5 nM), potent anti-HCV 2a activity (EC₅₀ = 98 nM), and high oral bioavailability in rat (100%) and dog (55%). The synthetic accessibility and properties of 3 support its potential as an anti-HCV agent and for interrogating the role of Cyp inhibition in a variety of diseases.