A new C2-symmetric heterobimetallic complex as a promoter for asymmetric Michael addition reactions
TL;DR: In this paper, a C2-symmetric chiral amino diol (1R,5R)-3-aza-3-benzyl-1,5-diphenyl pentan-1.5diol [(R,R)-I] has been synthesised by a modified procedure.
Abstract: A C2-symmetric chiral amino diol (1R,5R)-3-aza-3-benzyl-1,5-diphenyl pentan-1,5-diol [(R,R)-I] has been synthesised by a modified procedure. The heterobimetallic catalyst [I2AlLi] obtained by reaction of the amino diol [(R,R)-I] with LiAlH4, promotes asymmetric Michael addition of malonic esters and thiophenols to α,β-unsaturated compounds with high enantiomeric excess.
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TL;DR: In this article, the authors describe the use of catalysts possessing a number of reactive sites that operate synergistically in order to bring about highly selective transformations, and describe how to use such catalysts.
240 citations
TL;DR: A novel catalyst system based on a chiral strontium complex which promotes the catalytic asymmetric Michael addition reactions of malonates to enones has been developed and provides an efficient approach to the preparation of building blocks possessing various functional groups and possible sites for further functionalization.
Abstract: A novel catalyst system based on a chiral strontium complex which promotes the catalytic asymmetric Michael addition reactions of malonates to enones has been developed. The conjugate addition reactions proceeded smoothly in the presence of 5 mol % of the chiral strontium catalyst, at room temperature, to afford the desired adducts in high yields and excellent enantioselectivities. This method provides an efficient approach to the preparation of building blocks possessing various functional groups and possible sites for further functionalization.
100 citations
TL;DR: The use of nucleophiles bearing chiral centres, the use of α,β-unsaturated systems with the chirality at the γ position and the presence of chiral ligands or other chiral mediators are the more common sources for the control of asymmetry through Michael addition reactions.
93 citations
TL;DR: Dinuclear vanadium(v) complexes (R(a),S,S)- and show considerably higher catalytic activity than previously reported vanadium complexes for the oxidative coupling of 2-naphthols.
91 citations
TL;DR: The optimized reaction conditions yield Michael adducts in good yield with high enantiomeric excesses, which are quite effective for asymmetric Michael addition of nitro compounds, thiols, and amines.
90 citations
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Book•
01 Jan 1969
TL;DR: Inert Gases and Their Purification as discussed by the authors, inert gases and their purification are used for line design and operation of vacuum line equipment and their operation is described in detail.
Abstract: INERT ATMOSPHERE TECHINQUES. Bench--Top Inert--Atmosphere Techniques. Inert--Atmosphere Glove Boxes. Inert Gases and Their Purification. Purification of Solvents and Reagents. Vacuum Line Design and Operation. Pumps for Rough and High Vacuum. Pressure and Flow Measurement and Leak Detection. Joints, Stopcocks, and Valves. Specialized Vacuum--Line Equipment and Operations. Metal Systems. Metal Systems. Appendixes. Index.
1,418 citations
817 citations
Book•
01 Jun 1992
TL;DR: In this article, the authors present a survey of conjugate receptors and their interaction with the nucleophiles, as well as a classification of reaction types and their relations with each other.
Abstract: Introduction. Organization of the book. History. Nomenclature, classification of reaction types and survey of conjugate receptors. Mechanism of conjugate additions. The nucleophiles. Intramolecular reactions. Tandem reactions. Alkenals and Acyclic Alkenones. Introduction. Intermolecular reactions. Intramolecular reactions. Cycloalkenones. Introduction. Intermolecular reactions. Intramolecular reactions. Alkenoic Acids and their Derivatives. Introduction. Intermolecular reactions. Intramolecular reactions. alpha,beta-Unsaturated Lactones and Lactams. Introduction. Stabilized carbanions. Organocopper reagents. Other organometallic reagents. Free radicals. Heteronucleophiles. Other Systems. Introduction. Nitroalkenes. Alkenylsulfoxides, phosphonates and related compounds. Quinones. Alkenylsilanes. Ketene acetals. Alkenylphosphonium salts. Activated Alkynes. Alkynones. Alkynoic acid derivatives. Alkynyl sulfoxides, and related sustems. Index.
741 citations
TL;DR: In this article, the authors reported several carbon-carbon bond-forming reactions catalyzed by rare earth metal alkoxides and their application to a catalytic asymmetric nitroaldol reaction.
Abstract: In a recent paper, the authors reported that Zr(O-t-Bu){sub 4} was an efficient and convenient basic reagent in organic synthesis. However, all reactions examined were performed with stoichiometric quantities of the reagent. The authors envisioned that rare earth metal alkoxides would be stronger bases than group 4 metal alkoxides due to the lower ionization potential (ca. 5.4-6.4 eV) and the lower electronegativity (1.1-1.3) of rare earth elements; thus, the catalytic use of rare earth metal alkoxides in organic synthesis was expected. Although a variety of rare earth metal alkoxides have been prepared for the last three decades, to the authors knowledge, there have been few reports concerning the basicity of rare earth metal alkoxides. Herein, the authors report several carbon-carbon bond-forming reactions catalyzed by rare earth metal alkoxides and their application to a catalytic asymmetric nitroaldol reaction.
500 citations
TL;DR: In this article, a new class of ligands for asymmetric transition metal catalysis based on 2-(diphenylphosphino)benzoic acid was used in a mechanistically defined palladium-catalyzed reaction in which enantiodifferentiation was the result of selective ionization of substrates derived from cis-2-cycloalkene-1,4-diols.
Abstract: A new class of ligands for asymmetric transition metal catalysis based on 2-(diphenylphosphino)benzoic acid was used in a mechanistically-defined palladium-catalyzed reaction in which enantiodifferentiation was the result of selective ionization of substrates derived from cis-2-cycloalkene-1,4-diols. By making rational, stepwise changes in the ligand structure, the structural requirements for good asymmetric induction were probed. The absolute stereochemistry of the products was found to be related to the chirality of the ligand in a predictable fashion
444 citations