Strategies for Constructing Diverse Chiral Environments in Multimetallic Bifunctional Asymmetric Catalysis

Abstract

Recent advances from our group in the design and applications of multimetallic bifunctional asymmetric catalysts are described. Suitable design of chiral ligands and selection of metals were important to realize cooperative bimetallic catalysis. In this account, our strategies for constructing flexible and diverse chiral environments in multimetallic complexes for the rapid optimization of targeted reactions, such as tertiary nitroaldol kinetic resolution, cyclopropanation of electron-deficient olefins, cyano-ethoxycarbonylation of aldehydes, direct Mannich-type reactions, the nitro-Mannich reaction, the anti-selective nitroaldol reaction, and amination, are discussed in detail.

1 Introduction

2 Heterobimetallic Rare-Earth-Alkali Metal-BINOL Complexes

2.1 Background

2.2 Catalytic Kinetic Resolution of Tertiary Nitroaldols

2.3 Catalytic Asymmetric Cyclopropanation of Enones

2.4 Catalytic Asymmetric Cyano-ethoxycarbonylation

3 La Aryloxide/Li Aryloxide/pybox Complexes for Direct Catalytic Asymmetric Mannich-type Reactions

4 Heterobimetallic Transition Metal/Rare-Earth Metal/Dinucleating Schiff Base Complexes

4.1 syn-Selective Nitro-Mannich-type Reaction

4.2 anti-Selective Nitroaldol Reaction

5 Homobimetallic Nickel/Dinucleating Schiff Base Complex

6 Rare-Earth Metal/Amide Complexes for Catalytic Asymmetric Amination

7 Summary

asymmetric catalysis - asymmetric synthesis - bifunctional catalysis - rare-earth metals - Lewis acids

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Trichloromethyl carbinols were stereoselectively converted into azetidinecarboxylic acids; see reference 47.

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For related attempts to develop bifunctional asymmetric catalysts using heterobimetallic Schiff base complexes, see:

<A NAME="RA48108ST-52A">52a</A> Annamalai V. DiMauro EF. Carroll PJ. Kozlowski MC. J. Org. Chem.  2003,  68:  1973 ; and references cited therein See also:

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The structures of related heterobimetallic Cu/rare-earth metal/Schiff base complexes were unequivocally determined by X-ray crystallographic analysis; see:

<A NAME="RA48108ST-53A">53a</A> Koner R. Lee G.-H. Wang Y. Wei H.-H. Mohanta S. Eur. J. Inorg. Chem.  2005,  1500 

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<A NAME="RA48108ST-54">54</A> For a review on catalytic asymmetric nitro-Mannich reactions, see: Westermann B. Angew. Chem. Int. Ed.  2003,  42:  151 

For anti-selective catalytic asymmetric nitro-Mannich reactions with metal catalysts, see:

<A NAME="RA48108ST-55A">55a</A> Yamada K.-I. Moll G. Shibasaki M. Synlett  2001,  980 

<A NAME="RA48108ST-55B">55b</A> Knudsen KR. Risgaard T. Nishiwaki N. Gothelf KV. Jørgensen KA. J. Am. Chem. Soc.  2001,  123:  5843 ; and references cited therein

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With thio-ureas, see:

<A NAME="RA48108ST-55D">55d</A> Yoon TP. Jacobsen EN. Angew. Chem. Int. Ed.  2005,  44:  466 

<A NAME="RA48108ST-55E">55e</A> Xu X. Furukawa T. Okino T. Miyabe H. Takemoto Y. Chem. Eur. J.  2006,  12:  466 

<A NAME="RA48108ST-55F">55f</A> Robak MT. Trincado M. Ellman JA. J. Am. Chem. Soc.  2007,  129:  15110 

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With cinchona alkaloids, see:

<A NAME="RA48108ST-55H">55h</A> Palomo C. Oiarbide M. Laso A. López R. J. Am. Chem. Soc.  2005,  127:  17622 

For recent examples of chiral µ-oxo or µ-hydroxide multi-rare-earth-metal complexes, see:

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<A NAME="RA48108ST-56B">56b</A> Wooten AJ. Salvi L. Carroll PJ. Walsh PJ. Adv. Synth. Catal.  2007,  349:  561 

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<A NAME="RA48108ST-57D">57d</A> Arai T. Watanabe M. Yanagisawa A. Org. Lett.  2007,  9:  3595 

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<A NAME="RA48108ST-58A">58a</A> Ooi T. Doda K. Maruoka K. J. Am. Chem. Soc.  2003,  125:  2054 

<A NAME="RA48108ST-58B">58b</A> Risgaard T. Gothelf KV. Jørgensen KA. Org. Biomol. Chem.  2003,  1:  153 

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<A NAME="RA48108ST-70B">70b</A>

Mashiko T., Kumagai N., Shibasaki M.; manuscript in preparation.