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We report a practical synthesis of PI3K inhibitor GDC-0941. The synthesis was achieved using a convergent approach starting from a thienopyrimidine intermediate through a sequence of formylation and reductive amination followed by Suzuki-Miyaura cross-coupling. Metalation of the thienopyrimidine intermediate involving the intermediacy of triarylmagnesiates allowed formylation under noncryogenic conditions to produce the corresponding aldehyde. We also investigated aminoalkylation via a benzotriazolyl-piperazine substrate as an alternative to the reductive amination route. We evaluated both palladium and nickel catalyzed processes for the borylation and Suzuki-Miyaura cross-coupling. Final deprotection and salt formation afforded the API.

Ruthenium-catalyzed asymmetric homogeneous hydrogenation (AHH) is used as the key step of a multi-kilogram scale synthesis of an enantiomeric fluoropiperidine. The AHH of a tetrasubstituted b-fluoroenamide is carried out under mild conditions using a Ru/Josiphos catalyst with high ee (98%).