title: Solphos: a new family of efficient biaryl diphosphine ligands.
abstract: Solphos (7,7'-bis(diarylphosphino)-3,3',4,4'-tetrahydro-4,4'-dimethyl-8,8'-bis-2H-1,4-benzoxazine) is a new modular atropisomeric biaryl ligand with a very attractive activity profile. A technically feasible synthesis is described allowing the synthesis of various derivatives of enantiopure ligand on a technical scale. Very good catalytic performances have been demonstrated for the following transformations: Ru-catalyzed hydrogenation of various beta-keto esters (95-99 % ee, s/c up to 100,000), of acetyl acetone (>99 % ee, dl/meso>98:2), and of an exocyclic alpha,beta-unsaturated acid (98.6 % ee, s/c 250). In several cases, the nature of the PAr(2) moiety had a significant effect on the enantioselectivity. Furthermore, Rh and Ir Solphos complexes achieved high enantioselectivities for a novel synthesis of 3,3-disubstituted phthalides and the reductive coupling of alkynes with N-sulfonyl imines, respectively.
authors.affiliation: Solvias AG, P.O. Box, 4002 Basel, Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Kesselgruber
authors.forename: Matthias
authors.initials: M
authors.lastname: Lotz
authors.forename: Pierre
authors.initials: P
authors.lastname: Martin
authors.forename: Gianpietro
authors.initials: G
authors.lastname: Melone
authors.forename: Markus
authors.initials: M
authors.lastname: Müller
authors.forename: Benoît
authors.initials: B
authors.lastname: Pugin
authors.forename: Frédéric
authors.initials: F
authors.lastname: Naud
authors.forename: Felix
authors.initials: F
authors.lastname: Spindler
authors.forename: Marc
authors.initials: M
authors.lastname: Thommen
authors.forename: Paul
authors.initials: P
authors.lastname: Zbinden
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Blaser