Diels−Alder Exo Selectivity in Terminal-Substituted Dienes and Dienophiles: Experimental Discoveries and Computational Explanations

Lam, Yu-hong; Cheong, Paul Ha‐Yeon; Mata, J. M.; Stanway, Steven J.; Gouverneur, Véronique; Houk, K. N.

doi:10.1021/ja8079548

Cited by 111 publications

(67 citation statements)

References 115 publications

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“…Only when the allylzinc reagent carries an additional substituent at C2 will the pseudoaxial site be disfavored due to increased 1,3-diaxial strain. Previous work from our group also found 58 that high exo selectivity was observed in Diels–Alder reactions when the termini of the acyclic diene and dienophile involved in the shorter of the forming C–C bonds were both monoalkyl-substituted (Fig. 8B).…”

Section: Resultssupporting

confidence: 56%

Stereoselectivities of Histidine-Catalyzed Asymmetric Aldol Additions and Contrasts with Proline Catalysis: A Quantum Mechanical Analysis

et al. 2012

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Quantum mechanical calculations reveal the origin of diastereo- and enantioselectivities of aldol reactions between aldehydes catalyzed by histidine, and differences between related reactions catalyzed by proline. A stereochemical model that explains both the sense and the high levels of the experimentally observed stereoselectivity is proposed. The computations suggest that both the imidazolium and the carboxylic acid functionalities of histidine are viable hydrogen-bond donors that can stabilize the cyclic aldolization transition state. The stereoselectivity is proposed to arise from minimization of gauche interactions around the forming C–C bond.

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Section: Resultssupporting

confidence: 56%

Stereoselectivities of Histidine-Catalyzed Asymmetric Aldol Additions and Contrasts with Proline Catalysis: A Quantum Mechanical Analysis

et al. 2012

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“…[25] However, the endo selectivity in similar reactions of cyclopentadienes with the same In III /1 b catalyst strongly suggests that the steric model is not applicable in the current case. Usually, steric hindrance, imposed by either the substrate or the catalyst, has been proposed to account for the observed exo selectivity in Diels-Alder reactions.…”

Section: Angewandte Zuschriftenmentioning

confidence: 79%

Switchable Diastereoselectivity in Enantioselective [4+2] Cycloadditions with Simple Olefins by Asymmetric Binary Acid Catalysis

Zhang

Luo

et al. 2013

Angew Chem Int Ed

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Chiral 3,4-dihydro-2H-pyrans and tetrahydropyrans are versatile structural motifs of a number of bioactive natural products (e.g. epicalyxin F and sugiresinol), [1,2] fragrances (doremox), [3] and foodstuff flavorings ( Figure 1). [4] A straightforward approach to access this type of products is the catalytic asymmetric inverse-electron-demand Diels-Alder reaction between a,b-unsaturated carbonyl compounds and alkenes. [5][6][7][8] Though extensively explored in asymmetric catalysis, [9] this reaction has been limited to electron-rich alkenes, such as enol ethers, enamines, and cyclopentadienes. [10] Reactions with electronically unbiased simple alkenes would give the illustrated compounds directly (Figure 1), but have been rather unsuccessful. In fact, as a consequence of the intrinsic electronic/orbital constraints, intermolecular Diels-Alder reactions with simple olefins are generally difficult to achieve and require harsh conditions and long reaction times. [11] Hence, achieving a catalytic asymmetric version of the reaction with simple olefins remains elusive, despite the tremendous advances in Diels-Alder chemistry.

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“…29 The reaction takes place from the s-cis conformation of the dienophile as expected, as the diene is not substituted at the α-position, like in the current tigloyl-based dieneophile.…”

Section: ■ Results and Discussionmentioning

confidence: 73%

Stereoselective Synthesis of 1-Tuberculosinyl Adenosine; a Virulence Factor of Mycobacterium tuberculosis

et al. 2016

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Despite its status as one of the world’s most prevalent and deadly bacterial pathogens, Mycobacterium tuberculosis (Mtb) infection is not routinely diagnosed by rapid and highly reliable tests. A program to discover Mtb-specific biomarkers recently identified two natural compounds, 1-tuberculosinyl adenosine (1-TbAd) and N6-tuberculosinyl adenosine (N6-TbAd). Based on their association with virulence, the lack of similar compounds in nature, the presence of multiple stereocenters, and the need for abundant products to develop diagnostic tests, synthesis of these compounds was considered to be of high value but challenging. Here, a multigram-scale stereoselective synthesis of 1-TbAd and N6-TbAd is described. As a key-step, a chiral auxiliary-mediated Diels–Alder cycloaddition was developed, introducing the three stereocenters with a high exo endo ratio (10:1) and excellent enantioselectivity (>98% ee). This constitutes the first entry into the stereoselective synthesis of diterpenes with the halimane skeleton. Computational studies explain the observed stereochemical outcome.

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Diels−Alder Exo Selectivity in Terminal-Substituted Dienes and Dienophiles: Experimental Discoveries and Computational Explanations

Cited by 111 publications

References 115 publications

Stereoselectivities of Histidine-Catalyzed Asymmetric Aldol Additions and Contrasts with Proline Catalysis: A Quantum Mechanical Analysis

Stereoselectivities of Histidine-Catalyzed Asymmetric Aldol Additions and Contrasts with Proline Catalysis: A Quantum Mechanical Analysis

Switchable Diastereoselectivity in Enantioselective [4+2] Cycloadditions with Simple Olefins by Asymmetric Binary Acid Catalysis

Stereoselective Synthesis of 1-Tuberculosinyl Adenosine; a Virulence Factor of Mycobacterium tuberculosis

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