Highly Enantio- and Diastereoselective Hetero-Diels-Alder Reactions Catalyzed by New Chiral Tridentate Chromium(III) Catalysts

Dossetter, Alexander G.; Jamison, Timothy F.; Jacobsen, Eric N.

doi:10.1002/(sici)1521-3773(19990816)38:16<2398::aid-anie2398>3.0.co;2-e

Cited by 299 publications

(171 citation statements)

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“…(13)]. [27] These complexes, which are highly diastereoand enantioselective catalysts for the reaction of unactivated aldehydes, can catalyze the reaction of less nucleophilic dienes bearing fewer than two oxygen substituents. The adamantyl-substituted catalysts 19 a and 19 b gave the best results, and both aliphatic and aromatic aldehydes underwent HDA reactions.…”

Section: Chiral Transition and Lanthanide Metal Complexesmentioning

confidence: 99%

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Catalytic Asymmetric Hetero-Diels–Alder Reactions of Carbonyl Compounds and Imines

Jørgensen

2000

Angew. Chem. Int. Ed.

631

145

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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.

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Section: Chiral Transition and Lanthanide Metal Complexesmentioning

confidence: 99%

“…(27)]. [65] The TADDOL ± TiX 2 (X Cl, Br) complexes 53 were found to catalyze an enantioselective reaction giving the dihydroAngew.…”

Section: Inverse Electron Demand Reactionsmentioning

confidence: 99%

Catalytic Asymmetric Hetero-Diels–Alder Reactions of Carbonyl Compounds and Imines

Jørgensen

2000

Angew. Chem. Int. Ed.

631

145

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“…The nitroso-Diels-Alder reaction of pentadiene and 6-methyl-2-nitrosopyridine in the presence of [Cu(MeCN) 4 -(segphos)]PF 6 gave a mixture of 1-and 4-amino derivatives in a 3:1 ratio with up to 10% ee. The reactivity of the diene was increased, and (2Z,4E)-3-trimethylsilyloxy-2,4-hexadiene [4] (1a) was examined in the presence of a catalytic amount of [Cu(MeCN) 4 (segphos)]PF 6 .…”

mentioning

confidence: 99%

“…The reactivity of the diene was increased, and (2Z,4E)-3-trimethylsilyloxy-2,4-hexadiene [4] (1a) was examined in the presence of a catalytic amount of [Cu(MeCN) 4 (segphos)]PF 6 . Although this experiment gave complete regioselectivity[5] (4-silyloxy/5-silyloxy ≥ 99:1), the enantioselectivity (16% ee for the 4-silyloxy derivative) remained low.…”

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confidence: 99%

Catalytic Asymmetric Nitroso‐Diels–Alder Reaction with Acyclic Dienes

Yamamoto

2005

Angew Chem Int Ed

114

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Keywords amino alcohols; asymmetric catalysis; cycloaddition; dienes; nitroso compoundsThe nitroso-Diels-Alder reaction has long been a valuable synthetic operation for multistep syntheses given that the resulting adducts serve as 1-amino-4-hydroxy-2-ene derivatives after a single step. Subsequent to earlier studies by Kresze and co-workers[1] on the use of simple nitroso derivatives, many research groups have made significant contributions to the steady improvement of this methodology.[2] Recently, we enhanced this transformation to catalytic and enantioselective methods through the use of nitrosopyridine as a dienophile in the presence of a chiral copper catalyst.[3] Unfortunately, the new asymmetric reaction did not proceed as smoothly for acyclic dienes as it did for cyclic systems, which therefore limits its range of application. Herein, we report catalytic regio-, diastereo-, and enantioselective nitroso-Diels -Alder reactions of acyclic 2-silyloxy-1,3-dienes that have a broad substrate scope. The pathway for the present catalytic enantioselective transformation is outlined in Scheme 1.The nitroso-Diels-Alder reaction of pentadiene and 6-methyl-2-nitrosopyridine in the presence of [Cu(MeCN) 4 -(segphos)]PF 6 gave a mixture of 1-and 4-amino derivatives in a 3:1 ratio with up to 10% ee. The reactivity of the diene was increased, and (2Z,4E)-3-trimethylsilyloxy-2,4-hexadiene[4] (1a) was examined in the presence of a catalytic amount of [Cu(MeCN) 4 (segphos)]PF 6 . Although this experiment gave complete regioselectivity[5] (4-silyloxy/5-silyloxy ≥ 99:1), the enantioselectivity (16% ee for the 4-silyloxy derivative) remained low. Surprisingly, the low enantioselectivity was improved significantly by simply increasing the size of the silyl group (1aγ1bγ1c): Up to 98% ee in the presence of Cu I -segphos [6] and > 99% ee with [Cu(MeCN) 4 -(difluorophos)]PF 6 [7] were attained in the reaction of the triisopropylsilyl derivative 1c (Table 1).

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“…However, asymmetric cycloadditions involving weakly nucleophilic diene partners such as 2 and simple aldehydes were unknown, and as such this target provided the impetus to develop new methodology. In this context, it was discovered that novel (Schiff base)Cr(III) complexes such as 1 are remarkably reactive chiral Lewis acid catalysts, promoting cycloaddition between diene 2 and ynal 3 to establish the complete carbon framework of the central fragment while setting three of the four stereocenters simultaneously (Scheme 3) (14). Catalyst 1 was also applied successfully to the enantioselective synthesis of the right-hand fragment of FR901464.…”

Section: An Expanded Chiral Poolmentioning

confidence: 91%

Asymmetric Catalysis in Complex Target Synthesis

Taylor

Jacobsen

2004

ChemInform

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This article describes three distinct strategies by which stereochemically complex molecules are synthesized and the ways asymmetric catalysis can impact on all three. The development of general methods to prepare synthetically useful building blocks leads to an expanded ''chiral pool'' of potential starting materials for asymmetric synthesis. The possibility of discovering new reactions to access new types of building blocks is particularly attractive and serves to help define the frontiers of the field. Asymmetric catalysis can also be applied to diastereoselective synthesis such that the stereochemistry of the catalyst, and not that of the substrate, determines the relative configuration of the product. Finally, in reactions where multiple stereocenters are generated simultaneously or in tandem, catalyst and substrate control can operate in a complementary manner to achieve one of many possible stereochemical outcomes selectively.T he synthesis of both natural and unnatural organic compounds in optically active form is a central challenge in chemistry, especially in relation to the study of biologically active compounds. Natural products and synthetic pharmaceutical agents display a rich diversity of molecular structures that range from very simple to astonishingly intricate. A feature common to many such compounds is the presence of multiple stereocenters, giving rise to the possibility of large numbers of stereoisomers (2 n , where n is the number of stereocenters). The control of the relationship between stereocenters is therefore an essential element to the synthesis of many complex targets of interest.There are several ways to generate stereochemical complexity in a selective manner (Fig. 1). Chiral building block assembly, for which peptide synthesis represents the prototype, relies on the availability of the appropriate optically pure starting materials along with the reactions to elaborate and couple them. An alternative is diastereoselective synthesis, wherein new stereocenters are introduced into compounds bearing preexisting ones. The selectivity may arise either from the properties inherent to the substrate (substrate control) or from an external agent (reagent or catalyst control). A third strategy involves the use of transformations that simultaneously introduce multiple stereocenters in a single operation. For example, the coupling of two prochiral substrates may result in four (or more) stereochemical outcomes; enantio-and diastereoselective variants of such processes usually incorporate elements of catalyst and substrate control. Other methods for rapidly achieving stereochemical complexity under catalyst control are possible, including the desymmetrization of meso compounds and stereospecific reactions of geometrically defined precursors.Before the advent of efficient asymmetric synthetic methods, application of the chiral building block approach was constrained by the very limited pool of optically active compounds provided by nature in abundance (the ''chiral pool'') (1). Because of this c...

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Highly Enantio- and Diastereoselective Hetero-Diels-Alder Reactions Catalyzed by New Chiral Tridentate Chromium(III) Catalysts

Cited by 299 publications

References 1 publication

Catalytic Asymmetric Hetero-Diels–Alder Reactions of Carbonyl Compounds and Imines

Catalytic Asymmetric Hetero-Diels–Alder Reactions of Carbonyl Compounds and Imines

Catalytic Asymmetric Nitroso‐Diels–Alder Reaction with Acyclic Dienes

Asymmetric Catalysis in Complex Target Synthesis

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