Asymmetric ene reaction catalyzed by chiral organoaluminum reagent
TL;DR: In this paper, the asymmetric ene reaction of prochiral aldehydes with alkenes has been effected by chiral organoaluminum reagent providing optically active homoallylic alcohols in both enantiomeric forms with high enantiomic purity.
About: This article is published in Tetrahedron Letters.The article was published on 1988-01-01. It has received 121 citations till now. The article focuses on the topics: Enantiomeric excess & Ene reaction.
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TL;DR: A review of the development of catalytic asymmetric hetero-Diels-Alder reactions of carbonyl compounds and imines can be found in this paper, where a number of different chiral catalysts have been used.
Abstract: Asymmetric catalysis is a challenge for chemists: How can we design catalysts to achieve the goal of forming optically active compounds? This review provides the reader with an overview of the development of catalytic asymmetric hetero-Diels–Alder reactions of carbonyl compounds and imines. Since its discovery, the Diels–Alder reaction has undergone intensive development and is of fundamental importance for synthetic, physical, and theoretical chemists. The Diels–Alder reaction has been through different stages of development, and at the beginning of the 21st century catalytic Diels–Alder reactions are one of the main areas of focus. The preparation of numerous compounds of importance for our society is based on cycloaddition reactions to carbonyl compounds and imines. There are several parallels between the reactions of carbonyl compounds and those of imines, which, however, begin to vanish on entering the field of catalytic reactions. Why? From a mechanistic point of view some similarities can be drawn, but the synthetic development of catalytic enantioselective hetero-Diels–Alder reactions of imines are several years behind those of the carbonyl compounds. For hetero-Diels–Alder reactions of carbonyl compounds there a number of different chiral catalysts, and great progress has been achieved in developing enantioselective reactions for unactivated and activated carbonyl compounds. In contrast the development of catalytic enantioselective hetero-Diels–Alder reactions of imines is in its infancy and only few catalytic reactions have been published. This review will focus on the most important developments, and discuss the synthetic and mechanistic aspects of enantioselective hetero-Diels–Alder reactions of carbonyl compounds catalyzed by chiral Lewis acids. For the hetero-Diels–Alder reactions of imines, the diastereoselective reactions of optically substrates catalyzed by Lewis acids will be presented first, followed by the catalytic enantioselective reactions.
543 citations
TL;DR: Asymmetric catalysts that promote C-C bond-formation to ketones and ketimines should have high catalyst activity and enantioselectivity for synthetically more efficient addition to tetrasubstituted carbon synthesis.
Abstract: Chiral tertiary alcohols and R-tertiary amines are important building blocks of naturally occurring and artificial biologically active molecules. Although there are catalytic asymmetric oxidation and amination reactions to access these chiral building blocks, the catalytic asymmetric addition of carbon nucleophiles to ketones and ketimines, which can simultaneously construct a carbon skeleton and tetrasubstituted stereogenic center, is synthetically more efficient (Scheme 1). Realizing the catalytic asymmetric addition to ketones and ketimines (tetrasubstituted carbon synthesis), however, is generally more challenging than addition to aldehydes or aldimines (trisubstituted carbon synthesis) for two main reasons: (1) ketones and ketimines are significantly less reactive than aldehydes and aldimines; (2) enantio-face differentiation of ketones and ketimines is more difficult due to the smaller steric and electronic differences between the two substituents on prochiral carbons. Therefore, asymmetric catalysts that promote C-C bond-formation to ketones and ketimines should have high catalyst activity and enantioselectivity.
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References
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TL;DR: Etude de l'epoxydation du undecene-2ol-1 et du (E)-dimethyl-3,7 octadiene- 2,6ol- 1 (geraniol) par action of l'hydroperoxyde de t-butyle en presence de propanolate-2 de titane IV, de tartrate de diethyle and de tamis moleculaire as mentioned in this paper.
Abstract: Etude de l'epoxydation du (E)-undecene-2ol-1 et du (E)-dimethyl-3,7 octadiene-2,6ol-1 (geraniol) par action de l'hydroperoxyde de t-butyle en presence de propanolate-2 de titane IV, de tartrate de diethyle et de tamis moleculaire
406 citations
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TL;DR: The ene reaction is defined as the indirect substituting addition of a compound with a double bond (enophile) to an olefin with an allylic hydrogen (ene) as discussed by the authors.
Abstract: The ene reaction is defined as the indirect substituting addition of a compound with a double bond (enophile) to an olefin with an allylic hydrogen (ene). For a long time the reaction has been neglected and has remained overshadowed by the related Diels-Alder addition. It is shown that the ene reaction possesses wide scope and applicability ranging from industrial to biosynthetic processes. Preparative aspects are summarized and current views on the mechanism are discussed.
396 citations
TL;DR: In this article, a variety of substituted, fused and bridged ring systems, including natural products, are discussed systematically illustrating the possibilities, limitations, and common features of this cyclization reaction and its reverse ring-opening process.
Abstract: Thermal cyclizations of appropriate dienes, enynes and related unsaturated systems, some of them carried out on an industrial scale, demonstrate increasingly the preparative power of the intramolecular ene reaction. A variety of substituted, fused and bridged ring systems, including natural products, are thus easily accessible in a regio- and stereo-selective manner. Numerous examples are discussed systematically illustrating the possibilities, limitations, and common features of this cyclization reaction and its reverse ring-opening process.
332 citations
230 citations
87 citations