Practical Asymmetric Hydrogenation-Based Synthesis of a Class-Selective Histone Deacetylase Inhibitor

Recent Advances in the Enantioselective Synthesis of Chiral Amines via Transition Metal-Catalyzed Asymmetric Hydrogenation

Chiral amines are key structural motifs present in a wide variety of natural products, drugs, and other biologically active compounds. During the past decade, significant advances have been made with respect to the enantioselective synthesis of chiral amines, many of them based on catalytic asymmetric hydrogenation (AH). The present review covers the use of AH in the synthesis of chiral amines bearing a stereogenic center either in the α, β, or γ position with respect to the nitrogen atom, reported from 2010 to 2020. Therefore, we provide an overview of the recent advances in the AH of imines, enamides, enamines, allyl amines, and N-heteroaromatic compounds.

Copper-catalyzed borylative cyclization of γ,δ-unsaturated aromatic oxime esters to (borylmethyl)pyrrolidines

An efficient copper-catalyzed aminoborylation of γ,δ-unsaturated aromatic oxime esters with bis(pinacolato)diboron has been developed. A variety of α-(borylmethyl)pyrrolidine derivatives were constructed in high yields under mild conditions.

Stereoelectronic Effects in Ligand Design: Enantioselective Rhodium-Catalyzed Hydrogenation of Aliphatic Cyclic Tetrasubstituted Enamides and Concise Synthesis of (R)-Tofacitinib

We herein report the development of a conformationally defined, electron-rich, C₂ -symmetric, P-chiral bisphosphorus ligand, ArcPhos, by taking advantage of stereoelectronic effects in ligand design. With the Rh-ArcPhos catalyst, excellent enantioselectivities and unprecedentedly high turnovers (TON up to 10 000) were achieved in the asymmetric hydrogenation of aliphatic carbocyclic and heterocyclic tetrasubstituted enamides, to generate a series of chiral cis-2-alkyl-substituted carbocyclic and heterocyclic amine derivatives in excellent enantiomeric ratios. This method also enabled an efficient and practical synthesis of the Janus kinase inhibitor (R)-tofacitinib.

1,3-Dipolar cycloaddition reactions of phthalic anhydrides with an azomethine ylide

A series of phthalic anhydrides underwent a 1,3-dipolar cycloaddition reaction with N-benzylazomethine ylide to produce unstable spiro(isobenzofuran-1,5′-oxazolidin)-3-ones, which underwent a subsequent reductive ring-opening reaction to afford 1(3H)-isobenzofuranones.