Xyl-BINAP

Availability issues Concern with xyl-BINAP DIPEN ligand No known issues... 

Dynamic kinetic resolution is possible for a-alkyl or a-alkoxy cyclic ketones in the presence of KOH, which causes mutation of the stereogenic center syn-alco-hols were obtained selectively with high enantioselectivity using ruthenium-3,5-xyl-binap. Dynamic kinetic resolution of 2-arylcycloalkanones also proceeded with extremely high syn-selectivity and with high enantioselectivity using ruthenium-binap-diamine as catalyst (Table 21.23) [12, 139, 140]. 

Carbapenem antibiotics (29) can be manufactured from intermediates obtained by Ru(BINAP)-catalyzed reduction of a-substituted P-keto esters by a dynamic kinetic resolution (Scheme 12.8). 4-Acetoxy azetidinone (30) is prepared by a regioselective RuCl3-catalyzed acetoxylation reaction of 31 with peracetic acid 46 This process has been successful in the industrial preparation of the azetidinone 30 in a scale of 120 tons per year.47 The current process has changed ligands to 3,5-Xyl-BINAP (3c), and 31 is obtained in 98% ee and >94% de (substrate-to-catalyst ratio, or S/C ratio = 1,000).23... 

The diamine ligands that have shown the most consistent usage are DPEN (145) and diapen (146). The best bisphosphines ligands used to date have been axial bisphosphines ligands, such as BINAP (3a), tol-BINAP (3b), xyl-BINAP (3c),23 188 xyl-PhanePhos (127b),162 163 and xyl-P-Phos (120c).153... 

The use of an activation/deactivation protocol with a chiral poison, (R)-DM-DABN (148), has been achieved with ruthenium catalysts that contained rac-xyl-BINAP and rac-tol-BINAP with chiral diamine (S,S)-DPEN. Asymmetric hydrogenation of 2-napthyl methyl ketone (128, Ar = 2-Naph, R = Me) without 148 gave the alcohol with 41% ee, whereas an enantioselectivity of 91% ee is obtained with deactivator 148 present (Scheme 12.58).197... 

This system has been applied to the asymmetric hydrogenation see Hydrogenation) of methyl 3-oxobutanoate as illustrated in Table 3. Use of racemic (Xyl-BINAP)Ru complex with (5 )-DM-DABN gave essentially identical enantioselectivity to the use of enantioenriched (Xyl-BINAP)RuCl2(dmf) precatalyst. ... 

This system for the asymmetric hydrogenation of ketones has been employed in the asyimnetric activation using a racemic BINAP derivative. Combination of RuCl2[(5)-Xyl-BINAP](dmf) (Xyl = 3,5-C6H3-Me2) and (5,5)-DPEN gave the precatalyst RuCl2[( 8)-Xyl-BlNAP][(5, 5 )-DPEN], which exhibited 99% enantioselectivity in the reduction of 1-acetylnaphthone to the (f )-alcohol (equation 10). 

The catalyst composed of the mismatched ligands, (f )-Xyl-BlNAP and (5,5)-DPEN, was much slower and furnished the (5)-alcohol with 56% ee (equation 10). Employing racemic Xyl-BINAP and (5, 5 )-DPEN gave a 50 50 mixture of diastereomeric ruthenium complexes that reduced I -acetylnaphthone to the (f )-alcohol with excellent enantioselectivity (90%). 

In 2007, Li and List reported the asymmetric hydrogenation of a-arylaldehydes catalysed by [RuCl2(Xyl-BINAP)(DPEN)], providing the corresponding primary alcohols in excellent enantioselectivities and yields, as shown in Scheme 2.40. As an application of this reaction, the biologically active (5)-enantiomer of the non-steroidal anti-inflammatory drug, ibuprofen, could be... 

Moreover, deconstructing the tridentate architecture of the triphos ligand into chiral diphosphines such as xyl-BINAP or SEGPHOS provided an enantios-elective cycloisomerization with enantio-ratios up to 98 2 (Scheme 31) (68). 

Anilides, bearing a sterically demanding orfho-substituent, are known to exist as atropisomers due to a high rotational barrier around aryl-nitrogen single bond. The cationic rhodium(I)/xyl-BINAP complex-catalyzed enantioselective [2+2+2] cycloaddition of 1,6-diynes with trimethylsilylynamides afforded axiaUy chiral anilides with good to excellent enantioselectivity (Scheme 21.21) [25]. 

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