Pd-catalyzed asymmetric hydrogenation of fluorinated aromatic pyrazol-5-ols via capture of active tautomers

Pd-catalyzed asymmetric hydrogenation of fluorinated aromatic pyrazol-5-ols via capture of active tautomers.

An efficient palladium-catalyzed asymmetric hydrogenation of fluorinated aromatic pyrazol-5-ols has been developed via capture of the active tautomers. A wide variety of 2,5-disubstituted and 2,4,5-trisubstituted pyrazolidinones have been synthesized with up to 96% and 95% ee, respectively. The hydrogenation pathway includes Brønsted acid promoted tautomerization of pyrazol-5-ols and Pd-catalyz...

Synthesis of Chiral Fluorinated Hydrazines via Pd-Catalyzed Asymmetric Hydrogenation.

An enantioselective hydrogenation of fluorinated hydrazones has been achieved by employing [Pd(R)-DTBM-SegPhos(OCOCF3)2] as the catalyst, providing a general and convenient method toward chiral fluorinated hydrazines. A broad substrate scope including β-aryl-, γ-aryl-, and alkyl-chain-substituted hydrazones worked efficiently in high yields and up to 94% of enantioselectivity. The reductive ami...

Pd-catalyzed asymmetric hydrogenation of fluorinated aromatic pyrazol-5-ols via capture of active tautomers† †Electronic supplementary information (ESI) available. CCDC 1040656–1040658. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5sc00835b Click here for additional data file. Click here for additional data file.

Highly Enantioselective Pd-Catalyzed Asymmetric Hydrogenation of N-Diphenylphosphinyl Ketimines Enantioselective Pd-Catalyzed Asymmetric Hydrogenation of N-Diphenylphosphinyl Ketimines

Transition-metal-catalyzed asymmetric synthesis is a powerful and commonly used method for preparing a wide range of enantiomerically pure compounds.1 Among organo-transition-metal compounds, Pd complexes have become indispensable tools for both common and stateof-the art organic synthesis.2 Although a large number of Pd-based catalytic systems have been developed for many kinds of reactions, P...

Highly enantioselective Pd-catalyzed asymmetric hydrogenation of activated imines.

Pd/bisphosphines complexes are highly effective catalysts for asymmetric hydrogenation of activated imines in trifluoroethanol. The asymmetric hydrogenation of N-diphenylphosphinyl ketimines 3 with Pd(CF3CO2)/(S)-SegPhos indicated 87-99% ee, and N-tosylimines 5 could gave 88-97% ee with Pd(CF3CO2)/(S)-SynPhos as a catalyst. Cyclic N-sulfonylimines 7 and 11 were hydrogenated to afford the useful...