title: Iridium-catalyzed asymmetric hydrogenation yielding chiral diarylmethines with weakly coordinating or noncoordinating substituents.
abstract: 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.
authors: Department of Biochemistry and Organic Chemistry, Uppsala University, Box 576, SE-751 23 Uppsala, Sweden.
authors: Päivi
authors: P
authors: Tolstoy
authors: Mattias
authors: M
authors: Engman
authors: Alexander
authors: A
authors: Paptchikhine
authors: Jonas
authors: J
authors: Bergquist
authors: Tamara L
authors: TL
authors: Church
authors: Abby W-M
authors: AW
authors: Leung
authors: Pher G
authors: PG
authors: Andersson