Iridium-Catalyzed Asymmetric Hydrogenation Yielding Chiral Diarylmethines with Weakly Coordinating or Noncoordinating Substituents

• Published in: Journal of the American Chemical Society Vol. 131; no. 25; pp. 8855 - 8860
• Main Authors: Tolstoy, Päivi, Engman, Mattias, Paptchikhine, Alexander, Bergquist, Jonas, Church, Tamara L, Leung, Abby W.-M, Andersson, Pher G
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 01.07.2009; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Multidisciplinary; Kemi; NATURAL SCIENCES; NATURVETENSKAP; Physical Sciences; Science & Technology; N,P LIGANDS; MUSCARINIC RECEPTOR ANTAGONIST; CROSS-COUPLING REACTION; ENANTIOSELECTIVE HYDROGENATION; PHOSPHITE-OXAZOLINES; TRISUBSTITUTED OLEFINS; OXAZOLINE LIGANDS; AROMATIC-COMPOUNDS; ARYLBORONIC ACIDS; TETRASUBSTITUTED OLEFINS
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/ja9013375

Diarylmethine-containing stereocenters are present in pharmaceuticals and natural products, making the synthetic methods that form these chiral centers are important in industry. We have applied iridium complexes with novel N,P-chelating ligands to the asymmetric hydrogenation of trisubstituted olefins, forming diarylmethine chiral centers in high conversions and excellent enantioselectivities (up to 99% ee) for a broad range of substrates. Our results support the hypothesis that steric hindrance in one specific area of the catalyst is playing a key role in stereoselection, as the hydrogenation of substrates differing little at the prochiral carbon occurred with high enantioselectivity. As a result, excellent stereodiscrimination was obtained even when the prochiral carbon bore, for example, phenyl and p-tolyl groups.