Extending the Substrate Scope of Bicyclic P‐Oxazoline/Thiazole Ligands for Ir‐Catalyzed Hydrogenation of Unfunctionalized Olefins by Introducing a Biaryl Phosphoroamidite Group. Issue 8 (7th January 2015)

• Record Type: Journal Article
• Authors: Biosca, Maria; Paptchikhine, Alexander; Pàmies, Oscar; Andersson, Pher G.; Diéguez, Montserrat
• Is Part Of: Chemistry. Volume 21:Issue 8(2015)
• Page Start: 3455
• Page End: 3464
• Publication Date: 2015-01-07
• Subjects: asymmetric catalysis -- hydrogenation -- ligand design -- iridium -- P ligands; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201405361
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: This study identifies a series of Ir‐bicyclic phosphoroamidite–oxazoline/thiazole catalytic systems that can hydrogenate a wide range of minimally functionalized olefins (including E ‐ and Z ‐tri‐ and disubstituted substrates, vinylsilanes, enol phosphinates, tri‐ and disubstituted alkenylboronic esters, and α, β‐unsaturated enones) in high enantioselectivities ( ee values up to 99 %) and conversions. The design of the new phosphoroamidite–oxazoline/thiazole ligands derives from a previous successful generation of bicyclic N ‐phosphane–oxazoline/thiazole ligands, by replacing the N ‐phosphane group with a π‐acceptor biaryl phosphoroamidite moiety. A small but structurally important family of Ir‐phosphoroamidite–oxazoline/thiazole precatalysts has thus been synthesized by changing the nature of the N‐donor group (either oxazoline or thiazole) and the configuration at the biaryl phosphoroamidite moiety. The substitution of the N ‐phosphane by a phosphoroamidite group in the bicyclic N ‐phosphane–oxazoline/thiazole ligands extended the range of olefins that can be successfully hydrogenated. Abstract : Extending the range : A simple modification of previously developed N ‐phosphane–oxazoline/thiazole ligands extended the range of olefins that can be hydrogenated. High enantioselectivities were achieved, and the results obtained for most of the substrates were comparable to the best enantioselectivities reported so far (see scheme).