Solphos: a new family of efficient biaryl diphosphine ligands.

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.

From a chiral switch to a ligand portfolio for asymmetric catalysis.

This Account is divided into two sections. In the first section, the development of an enantioselective manufacturing process for ( S)-metolachlor, the active ingredient of the grass herbicide Dual Magnum, is described. This is today's largest application of asymmetric catalysis, and the Ir-Xyliphos hydrogenation catalyst achieves unprecedented 2 millions turnovers.

Exploring stereogenic phosphorus: synthetic strategies for diphosphines containing bulky, highly symmetric substituents.

Diphosphine ligands bearing highly symmetric, bulky substituents at a stereogenic P atom were prepared, exploiting established protocols, which include the use of chiral synthons such as 3,4-dimethyl-2,5-diphenyl-1,3,2-oxazaphospholidine-2-borane (3a) and phenylmethylchlorophosphine borane (10) and the enantioselective deprotonation of dimethylarylphosphine boranes. However, only (Bu(t)())(Me)PCH(2)CH(2)P(Bu(t)Me (8a) could be prepared from 3a. The diphosphines (S,S)-1,2-bis(mesitylmethylphosphino)ethane, ((S,S)-8b) and (S,S)-1,2-bis(9-anthrylmethylphosphino)ethane ((S,S)-8c), which contain 2,6-disubstituted aryl P-substituents, were prepared by Evans' sparteine-assisted enantioselective deprotonation of P(Ar)(Me)(2)(BH(3)) (Ar = mesityl or 9-anthryl), but the enantioselectivity did not exceed 37% ee.