Efficient Chiral Ligands Research Articles

Synthesis of optically active 2-(diarylphosphino)-1,1'-binaphthyls, efficient chiral monodentate phosphine ligands

Synthesis of optically active 2-(diarylphosphino)-1,1'-binaphthyls, efficient chiral monodentate phosphine ligands

Asymmetric Reactions Catalyzed by Chiral Metal Complexes. LVII. Synthesis of Efficient Chiral Bisphosphine Ligands, Modified DIOPs, (4R,5R)-4-(Diaryl- or dialkylphosphino)methyl-5-(diarylphosphino)methyl-2,2-dimethyl-1,3-dioxolanes, and Their Use in Rhodium(I)-Catalyzed Asymmetric Hydrogenations.

Modified DIOPs, (4R, 5R)-4-(diaryl- or dialkylphosphino)methyl-5-(diarylphosphino)methyl-2, 2-dimethyl-1, 3-dioxolanes, were prepared on the basis of our design concept, and used as ligands for the rhodium(I)-catalyzed asymmetric hydrogenations of ketopantolactone, itaconic acid, demethyl itaconate, and β-aryl-substituted itaconic acid derivatives. A neutral rhodium(I)-complex of (4R-trans)-dicyclohexyl[[5-[(diphenylphosphino)methyl]-2, 2-dimethyl-1, 3-dioxolan-4-yl]methyl]phosphine (DIOCP) bearing both a dicyclohexylphosphino group and a diphenylphosphino group was found to be a more efficient catalyst than the original DIOP in the asymmetric hydrogenation of ketopantolactone. Modified DIOPs bearing electron-donating groups at their para positions were efficient ligands for the rhodium(I)-catalyzed asymmetric hydrogenations of itaconic acid and its derivatives; in particular, (4R-trans)-[(2, 2-dimethyl-1, 3-dioxolane-4, 5-diyl)bis(metylene)]bis[bis(4'-methoxy-3', 5'-dimethylphenyl)phosphine] (MOD-DIOP) bearing both a p-methoxy group and two m, m'-methyl groups on each phenyl group showed much higher enantioselectivity and catalytic activity than DIOP.

Design Concepts for Developing Highly Efficient Chiral Bisphosphine Ligands in Rhodium-Catalyzed Asymmetric Hydrogenations

Several efficient asymmetric hydrogenations catalyzed by chiral bisphosphine-rhodium complexes were developed with the modification of bisphosphine ligands on the basis of our designing concept. 1. Introduction 2. The Respective Control Concept. A Proposal for the Development of Highly Efficient Chiral Bisphosphine Ligands 2.1. Preliminary Considerations 2.2. The Design of the Highly Efficient Bisphosphine Ligand BCPM 2.3. Experimental Confirmation of the Respective Control Concept 3. Application of the Designing Concept to C 2-Symmetric Bisphosphines 3.1. Development of Modified DIOP Ligands 3.2. Application to 1,2- and 1,3-Substituted Bisphosphines 3.3. Newly Designed 1,3-Substituted Bisphosphines 4. Application to the Practical Asymmetric Syntheses of Optically Active Medicines 5. Mechanistic Considerations of the Basis of the Correlation between Chirality of the Catalyst and Absolute Configuration of the Hydrogenation Product 5.1. Mechanism of Asymmetric Hydrogenation of Olefins 5.2. Mechanism of Asmmetric Hydrogenation of Ketones 6. Conclusion

Development of Modified Chiral Dioxolane Bisphosphine Ligands and Their Use in Efficient Asymmetric Synthesis of Naturally Occurring Lignans

This review deals with our recent works on the development of efficient chiral bisphisphine ligands, modified DIOPs, bearing a dioxolane framework and their application to the asymmetric total synthesis of naturally occurring lignans such as (+)-collinusin, (−)-deoxypodophyllotoxin, and (+)-neoisostegane using rhodium(I)-catalyzed asymmetric hydrogenation of itaconic acid derivatives as a key step. Related asymmetric total syntheses of lignans using an equimolar amount of chiral sources are also reviewed

ChemInform Abstract: Design of Super Catalysts for Asymmetric Hydrogenations and Their Utilization in Practical Asymmetric Syntheses

Recently, we have proposed a new designing concept, “Respective Control Concept”, for developing highly efficient chiral bisphosphine ligands. On the basis of our concept, new chiral bisphosphine ligands, BCPM, MOD-BPPM, MOD-DIOP, etc. have been synthesized. Their rhodium complexes have been found to show very high catalytic activity and enantioselectivity in the asymmetric hydrogenations of prochiral carbonyl and olefinic compounds. Practical asymmetric syntheses of useful biologically active compounds have been realized by using these hydrogenations as key reactions.

超効率不斉水素化触媒の開発と実用的不斉合成への応用

Recently, we have proposed a new designing concept, “Respective Control Concept”, for developing highly efficient chiral bisphosphine ligands. On the basis of our concept, new chiral bisphosphine ligands, BCPM, MOD-BPPM, MOD-DIOP, etc. have been synthesized. Their rhodium complexes have been found to show very high catalytic activity and enantioselectivity in the asymmetric hydrogenations of prochiral carbonyl and olefinic compounds. Practical asymmetric syntheses of useful biologically active compounds have been realized by using these hydrogenations as key reactions.

THE ENANTIOSELECTIVE ABILITY OF CHIRAL DIPHOSPHINE–RUTHENIUM COMPLEX IN ASYMMETRIC DEHYDROGENATION OF SECONDARY ALCOHOLS

Abstract (−)-2,3-O-Isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)buthane(diop) was found to be an efficient chiral ligand on using in Ru(II) catalyzed enantioselection of racemic alcohols with unsaturated additives. The dehydrogenation of PhEtCHOH by Ru2Cl4((−)-diop) with PhCH=CHCOPh at 165°C resulted in the formation of S-(−)-PhEtCHOH(11.0%e.e. at Conv.=56.8%).