Efficient and reliable amplification of chirality has borne its greatest fruit with transition metal-catalyzed reactions since enantiocontrol may often be imposed by replacing an achiral or chiral racemic ligand with one that is chiral and scalemic While the most thoroughly developed enantioselective transition metal-catalyzed reactions are those involving transfer of oxygen (epoxidation and dihydroxylation)1,2 and molecular hydrogen,3 the focus of this review is on the area of enantioselective transition metal-catalyzed allylic alkylations which may involve C-C as well as C-X (X ) H or heteroatom) bond formation4-9 The synthetic utility of transitionmetal-catalyzed allylic alkylations has been soundly demonstrated since its introduction nearly three decades ago10-21 In contrast to processes where the allyl moiety acts as the nucleophilic partner, we will limit our discussion to processes which result in nucleophilic displacements on allylic substrates (eq 1) Such reactions have been recorded with a broad

http://web4.uwindsor.ca/users/j/jlichaa/reference.nsf/0/10ff8b04ff3a317885256d88005720f6/$FILE/cr-1996-96-395-allylpd-asym.pdf

Asymmetric Transition Metal-Catalyzed Allylic Alkylations.

The increasing demand to produce enantiomerically pure pharmaceuticals, agrochemicals, flavors, and other fine chemicals has advanced the field of asymmetric catalytic technologies.1,2 Among all asymmetric catalytic methods, asymmetric hydrogenation utilizing molecular hydrogen to reduce prochiral olefins, ketones, and imines, have become one of the most efficient methods for constructing chiral compounds.3 The development of homogeneous asymmetric hydrogenation was initiated by Knowles4a and Horner4b in the late 1960s, after the discovery of Wilkinson’s homogeneous hydrogenation catalyst [RhCl(PPh3)3]. By replacing triphenylphosphine of the Wilkinson’s catalystwithresolvedchiralmonophosphines,6Knowles and Horner reported the earliest examples of enantioselective hydrogenation, albeit with poor enantioselectivity. Further exploration by Knowles with an improved monophosphine CAMP provided 88% ee in hydrogenation of dehydroamino acids.7 Later, two breakthroughs were made in asymmetric hydrogenation by Kagan and Knowles, respectively. Kagan reported the first bisphosphine ligand, DIOP, for Rhcatalyzed asymmetric hydrogenation.8 The successful application of DIOP resulted in several significant directions for ligand design in asymmetric hydrogenation. Chelating bisphosphorus ligands could lead to superior enantioselectivity compared to monodentate phosphines. Additionally, P-chiral phosphorus ligands were not necessary for achieving high enantioselectivity, and ligands with backbone chirality could also provide excellent ee’s in asymmetric hydrogenation. Furthermore, C2 symmetry was an important structural feature for developing new efficient chiral ligands. Kagan’s seminal work immediately led to the rapid development of chiral bisphosphorus ligands. Knowles made his significant discovery of a C2-symmetric chelating bisphosphine ligand, DIPAMP.9 Due to its high catalytic efficiency in Rh-catalyzed asymmetric hydrogenation of dehydroamino acids, DIPAMP was quickly employed in the industrial production of L-DOPA.10 The success of practical synthesis of L-DOPA via asymmetric hydrogenation constituted a milestone work and for this work Knowles was awarded the Nobel Prize in 2001.3k This work has enlightened chemists to realize * Corresponding author. 3029 Chem. Rev. 2003, 103, 3029−3069

New Chiral Phosphorus Ligands for Enantioselective Hydrogenation

Chiral nitrogen-containing compounds are widely distributed in nature and include many biologically important molecules (Chart 1). In these compounds, the nitrogen-containing units are known to play important roles for their bioactivities. For the synthesis of these chiral nitrogen-containing building blocks, use of imines as electrophiles is the most promising and convenient route.1 While many approaches using chiral imines or chiral nucleophiles have been reported,1 these diastereoselective reactions have some disadvantages. First, the procedures to introduce chiral auxiliaries to substrates and to remove them after the diastereoselective reactions are often tedious. Second, more than stoichiometric amounts of chiral sources are needed to obtain chiral compounds according to these reactions. On the other hand, catalytic enantioselective reactions provide the most efficient methods for the synthesis of chiral compounds,2 because large quantities of chiral compounds are expected to be prepared using small amounts of chiral sources. While much progress has been made recently in catalytic enantioselective reactions of aldehydes and ketones such as aldol,3 allylation,4 Diels-Alder,5 cyanation reactions,6 reduction,1b,2b etc., progress in catalytic enantioselective reactions of imines is rather slow. There are some difficulties in performing catalytic enantioselective reactions of imines. For example, in the cases of chiral Lewis acid promoted asymmetric Shū Kobayashi was born in 1959 in Tokyo, Japan. He studied chemistry at the University of Tokyo and received his Ph.D. in 1988 (Professor T. Mukaiyama). After spending 11 years at Science University of Tokyo (SUT), he moved to Graduate School of Pharmaceutical Sciences, University of Tokyo, in 1998. His research interests include development of new synthetic methods, development of novel catalysts (especially chiral catalysts), organic synthesis in water, solid-phase organic synthesis, total synthesis of biologically interesting compounds, and organometallic chemistry. He received the first Springer Award in Organometallic Chemistry in 1997.

https://chemistry.mdma.ch/hiveboard/picproxie_docs/000499541-cr980414z.pdf

Catalytic enantioselective addition to imines.

http://aether.cmi.ua.ac.be/artikels/Artikels%20Gitte/Artikels/Reviews/Trans.%20Metal.%20catal.%20reactions%20Chem.%20rev.%20042127.pdf

Transition-Metal-Catalyzed Reactions in Heterocyclic Synthesis

Transition-Metal-Catalyzed C−S, C−Se, and C−Te Bond Formation via Cross-Coupling and Atom-Economic Addition Reactions

Stereo- and Regioselectivity in Palladium-Catalyzed Allylic Etherification

Palladium(0)-based approach to functionalized C-glycopyranosides

The imines ArC(Me)NCH2Ph (Ar = Ph, 2-MeO-C6H4, 3-MeO-C6H4, 4-MeO-C6H4) are hydrogenated to the corresponding amines with extremely high enantioselectivities up to 96% under very mild conditions, using rhodium complexes associated with sulfonated bdpp.

Paul Lhoste

Papers

Stereo- and Regioselectivity in Palladium-Catalyzed Allylic Etherification

Palladium(0)-based approach to functionalized C-glycopyranosides

Rhodium(I)-sulfonated-bdpp catalysed asymmetric hydrogenation of imines in aqueous-organic two-phase solvent systems

Allyl ethyl carbonate/palladium (0), a new system for the one step conversion of alcohols into allyl ethers under neutral conditions

Synthesis of allyl aryl sulphides by palladium(0)-mediated alkylation of thiols