BIPHEP

Scheme 15 Iridium-catalyzed hydrogen-mediated coupling of alkyl-substituted alkynes to activated ketones and aldehydes. Conditions a ligand = BIPHEP, solvent = toluene, T = 80 °C b ligand = DPPF, solvent = toluene, T = 60 °C c ligand = BIPHEP, solvent = DCE,...

Figure 4 Chiral Pd complexes (a) PdBr(p-CNC6H4)( S -MeO-Biphep) (b) PdBr(C6F5)( S -MeO-Biphep). Potential aromatic 7r-7r stacking interactions are indicated by arrows.

Iridium-catalyzed transfer hydrogenation of aldehyde 73 in the presence of 1,1-dimethylallene promotes tert-prenylation [64] to form the secondary neopentyl alcohol 74. In this process, isopropanol serves as the hydrogen donor, and the isolated iridium complex prepared from [Ir(cod)Cl]2, allyl acetate, m-nitrobenzoic acid, and (S)-SEGPHOS is used as catalyst. Complete levels of catalyst-directed diastereoselectivity are observed. Exposure of neopentyl alcohol 74 to acetic anhydride followed by ozonolysis provides p-acetoxy aldehyde 75. Reductive coupling of aldehyde 75 with allyl acetate under transfer hydrogenation conditions results in the formation of homoallylic alcohol 76. As the stereochemistry of this addition is irrelevant, an achiral iridium complex derived from [Ir(cod)Cl]2, allyl acetate, m-nitrobenzoic acid, and BIPHEP was employed as catalyst (Scheme 5.9). 

The in situ generation of CuH from organosilanes in the presence of either a BIPHEP (99) or a SEGPHOS (100) type ligand represents a general method for the asymmetric hydrosilylation of aryl alkyl ketones at low temperatures. 

R)-liINAP-RuBr2 can be successfully applied to the enantioselective hydrogenation of /i-kelo esters in the synthesis of (+)-(2R,3 W)-corynomycolic acid 115. ( S )-MeO-BIPHEP-RuBr2 was used in a similar manner in the synthesis of (R)-fluoxetine (116, Prozac ) and (S)-duloxetine (117).648... 

Modification of the electronic and steric properties of BINAP, BIPHEMP, and MeO-BIPHEP can lead to the development of new efficient atropisomeric ligands (Figure 1). In fact, Takaya has found that a modified BINAP... 

Figure 2 Water-soluble biphep ligand and polymer-supported BINAP ligands.

Using RuCl3/CK)-MeO-BIPHEP catalytic system, the /Uhydroxy ester, a key intermediate to vWF receptor antagonists Sulfobacin A, was produced through asymmetric hydrogenation in 96% yield and 99% ee (Scheme 8).266 The... 

BINAP system with excellent ee s. For example, 0// 0-bromoacetophenone can be converted into the corresponding chiral alcohol with 96% ee (Equation (72)). However, this type of substrate can be hydrogenated more effectively with the Ru/chiral phosphine/diamine system.279 Asymmetric hydrogenation of phenylthioketones has been realized with Ru catalysts. BINAP, MeO-BIPHEP,280 BDPP281 and Me-CnrPHOS,62c are efficient for this transformation (Table 17). 

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