Extending the Substrate Scope of Bicyclic P-Oxazoline/Thiazole Ligands for Ir-Catalyzed Hydrogenation of Unfunctionalized Olefins by Introducing a Biaryl Phosphoroamidite Group

Identifier:  PC:1254

Handle: https://hdl.handle.net/20.500.11797/PC1254

Authors:  Montserrat Diéguez; Pher G. Andersson; Alexander Paptchkhine; Maria Biosca; Oscar Pàmies

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 a,b-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 p-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 Ndonor 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.