Asymmetric hydrogenation of .beta.-keto carboxylic esters. A practical, purely chemical access to .beta.-hydroxy esters in high enantiomeric purity

Ligand Design for Catalytic Asymmetric Reduction

“…66 This subject is discussed in Section 1.4. 3 ], 67 and other in situ formed (R)-BINAP-Ru complexes 70 are successfully used for hydrogenation of b-keto esters, resulting in the R b-hydroxy esters in >99% ee (Figure 1.13). An intermediate for the synthesis of carbapenem antibiotics is produced industrially by this method.…”

“…18,67,68 However, simple unfunctionalized ketones are totally inert to this catalyst system, because the substrates are unable to stabilize the transition state by forming a chelate structure (Figure 1.15). 21 A combined system of trans-RuCl 2 (binap)(dpen) and alkaline base [84][85][86] or trans-RuH(Z 1 -BH 4 )-(binap)(dpen) 87 with or without a base exhibits excellent catalytic performance in asymmetric hydrogenation of a variety of simple ketones.…”

Asymmetric Hydrogenation and Transfer Hydrogenation of Ketones

“…While for the AH of -alkyl -ketoesters high enantioselectivities can be attained by using the Ru-BINAP system, for the analogous -aryl ketoesters much more inferior ee values were obtained (Noyori et al, 1987). However, the highly enantioselective hydrogenation of a wide range of -aryl ketoesters 29 in the homogenous ionic liquid L26/methanol system was possible with Ru catalysts bearing 4,4'-substituted BINAP ligands L27 (Fig.…”

“…Since the application of very efficient, chiral BINAP-derived ruthenium complexes in the AH of functionalized ketones ( -keto esters) at a high enantioselectivity level in the homogenous phase (Noyori et al, 1987), the development of more robust and reactive molecular catalysts is still highly desirable. Furthermore, because of the structural and functional diversity of organic substrates, no universal catalysts exist.…”

Synthesis of achiral and new chiral crown ethers containing a triphenylphosphane unit

“…Trivalent phosphane compounds have gained great attention in organic chemistry since 1948 [1][2][3][4][5][6][7][8] due to their complexing ability and their potential use as catalysts in homogenous reactions, such as hydrogenation 9,10 for example. Although P-heterocyclic ligands are becoming the subjects of a more and more important research area, However, with most of these reported methods the phosphane is difficult to purify.…”