This review focuses on a new concept in catalytic asymmetric reactions that was first realized for the use of heterobimetallic complexes. As these heterobimetallic complexes function as both a Bronsted base and as a Lewis acid, just like an enzyme, they make possible a variety of efficient catalytic asymmetric reactions. This heterobimetallic concept should prove to be applicable to a variety of new asymmetric catalyses. The first part of this review describes the development of rare-earth–alkali metal complexes such as LnM3tris(binaphthoxide) complexes (LnMB, Ln = rare-earth metal, M = alkali metal), which are readily prepared from the corresponding rare-earth trichlorides or rare-earth isopropoxides, and their application to catalytic asymmetric synthesis. By using a catalytic amount of LnMB complexes several asymmetric reactions proceed efficiently to give the corresponding desired products in up to 98% ee: LnLB-catalyzed asymmetric nitroaldol reactions (L = Li), LnSB-catalyzed asymmetric Michael reactions (S Na), and LnPB-catalyzed asymmetric hydrophosphonylations of either imines or aldehydes (P K). Applications of these heterobimetallic catalysts to the syntheses of several biologically and medicinally important compounds are also described. Spectral analyses and computational simulations of the asymmetric reactions catalyzed by the heterobimetallic complexes reveal that the two different metals play different roles to enhance the reactivity of both reaction partners and to position them. From mechanistic considerations, a useful activation of the heterobimetallic catalyses was realized by addition of alkali metal reagents. The second part describes the development of another type of heterobimetallic catalysts featuring Group 13 elements such as Al and Ga as the central metal. Among them, the AlLibis(binaphthoxide) complex (ALB) is an effective catalyst for asymmetric Michael reactions, tandem Michael–aldol reactions, and hydrophosphonylation of aldehydes.

Asymmetric Catalysis with Heterobimetallic Compounds

Chiral lanthanide complexes: coordination chemistry and applications.

Tetrahedron report number 213

Metal-catalyzed reductive coupling reactions of aryl halides and (pseudo)halides with carbonyl-type compounds have undergone an impressive development within the last years. These methodologies have shown to be a powerful alternate strategy, practicality aside, to the use of stoichiometric, well-defined, and, in some cases, air-sensitive organometallic species. In this Minireview, the recent findings in this field are summarized, with particular emphasis on the mechanistic interpretation of the results and future aspects of this area of expertise.

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Metal‐Catalyzed Reductive Coupling Reactions of Organic Halides with Carbonyl‐Type Compounds

Selective tin and zinc mediated allylations of carbonyl compounds in aqueous media

L'amalgame de cerium est un reactif efficace pour la preparation chimioselective d'alcools homoallyliques a partir d'halogenures allyliques et de composes carbonyles. Ce meme reactif est utilise dans des reactions de type Reformatsky. Les reactifs organiques du Ce(III) generes par reaction d'organolithiens avec CeI 3 ou CeCl 3 sont moins basiques que les organolithiens et les reactifs de Grignard et reagissent avec divers composes carbonyles

Carbon-carbon bond-forming reactions using cerium metal or organocerium(III) reagents

This review deals with the utilization of elements of rare earth series in organic synthesis. Emphasis is made on the synthetically useful reactions which are not easily achievable with the reagents of main group and d-block elements.

Yoshinori Tawarayama

Papers

Carbon-carbon bond-forming reactions using cerium metal or organocerium(III) reagents

Organic Synthesis Using Lanthanoid Elements

The reaction of allyl iodide with ketones in the presence of cerium amalgam. An efficient method for the preparation of homoallylic alcohols

Organic synthesis using lanthanoid elements