The synthesis of P-stereogenic MOP analogues and their use in rhodium catalysed asymmetric addition

Setting P-Donor Ligands into Context: An Application of the Ligand Knowledge Base (LKB) Approach

“…Figure 2 focuses on the area around L1-L12 and identifies ligands lying nearby by their numbers (see supporting information Table S2 for details). The parent phosphametallocenes L1 and L2 10,11e,11f,15 lie close to the MOP phosphonites (L11, L12) reported by Higham et al,12,16 and also reasonably close to the phosphinines 11,14,17 L3-L5, with the slightly bulkier and more electron-rich L6 further removed. In addition, phosphametallocenes L1, L2 and MOP-phosphonites L11, L12 lie close to phosphite and phosphonite ligands such as P(OPh 3 ) 3 , 229, and related bridged structures 288, 289 (red diamonds, see Scheme 2 for structures, Table S2 for ligand numbers) and pyrrolyl-substituted aminophosphines, such as P(pyrr) 3 , 294, and the related structures 305, 307 (turquoise inverted triangles).…”

Simple unprecedented conversion of phosphine oxides and sulfides to phosphine boranes using sodium borohydride

“…We ourselves have reported several cases where 40 syntheses failed because the required reduction could not be placed at any point in the reaction sequence. 8 The avoidance of stereochemical control problems in oxide reductions was emphasised by Buono and co-workers as one of the advantages of their recent P-stereogenic phosphine borane synthesis. Once formed, the phosphines are relatively reactive (sometimes violently so) and are often converted to, and stored as, the corresponding phosphine boranes, from which they are easily deprotected, with stereocontrol, by a number of methods.…”

Synthesis of binaphthyl based phosphine and phosphite ligands

“…A different synthetic alternative was applied to a number of other P-stereogenic MOP analogues with different P-substituents. [115][116][117] This method proceeded via methylation of monotriflated (R)-BINOL and direct coupling of the resulting methoxy triflate with a secondary phosphine using the nickel/dppe catalyst to give a mixture of diastereomers, which were separated as the protected phosphine boranes by flash chromatography. The borane protecting groups were then removed by the addition of a base to give the desired diastereomerically pure phosphine products 90 (Fig.…”

“…The MOP analogues 90 were applied in rhodium-catalysed asymmetric addition of boronic acids to aldehydes, wherein the authors have not been able to improve previous results obtained with MeO-MOP. 117 Buchwald expanded the family of P-chiral monophosphine ligands synthesizing a set of 2-(alkylphenylphosphine)-2 0 -(dimethylamino)-1,1 0 -binaphthyl (MAP) compounds which provided up to 96% ee in palladium-catalysed asymmetric vinylation of enolates and in ketone arylation. 118 The BINOL carba-analogue, 2,2 0 -dimethyl-1,1 0 -binaphthyl, was also demonstrated to be a relevant building block for enantioselectivity induction in asymmetric catalysis.…”