The control of remote asymmetric centres via reduction of acyclic carbonyl functions

Sailes, Helen; Whiting, Andrew

doi:10.1039/b000155o

Cited by 37 publications

(9 citation statements)

References 117 publications

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“…[1,2] Although there are numerous examples of this phenomenon, a significant limitation with this type of process is the ability to predict the manner in which the chiral group attains proximity to the reactive site in order to translate stereochemical information. The inherent challenge associated with this requirement provided the incentive for the development of a new process where the elements of stereocontrol could be conserved in a predictable manner.…”

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confidence: 99%

“…The inherent challenge associated with this requirement provided the incentive for the development of a new process where the elements of stereocontrol could be conserved in a predictable manner. [1,2] Herein, we describe a new approach to long-range asymmetric induction using the diastereoselective temporary silicon-tethered (TST) ring-closing-metathesis (RCM) reaction of mixed bisalkoxy silanes 1, derived from an allylic and prochiral alcohol, for the construction of cis-1,4-silaketals 2 (Scheme 1; n = 0). This methodology was also extended to higher homologues (where n = 1-4), which resulted in the formation of the opposite trans diastereoisomer.…”

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confidence: 99%

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Diastereoselective Temporary Silicon‐Tethered Ring‐Closing‐Metathesis Reactions with Prochiral Alcohols: A New Approach to Long‐Range Asymmetric Induction

2003

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The ability to control stereochemistry in substrates where the reactive elements are distal represents a fundamentally important area of investigation that is commonly referred to as long-range asymmetric induction. [1,2] Although there are numerous examples of this phenomenon, a significant limitation with this type of process is the ability to predict the manner in which the chiral group attains proximity to the reactive site in order to translate stereochemical information. The inherent challenge associated with this requirement provided the incentive for the development of a new process where the elements of stereocontrol could be conserved in a predictable manner.[1, 2] Herein, we describe a new approach to long-range asymmetric induction using the diastereoselective temporary silicon-tethered (TST) ring-closing-metathesis (RCM) reaction of mixed bisalkoxy silanes 1, derived from an allylic and prochiral alcohol, for the construction of cis-1,4-silaketals 2 (Scheme 1; n = 0). This methodology was also extended to higher homologues (where n = 1-4), which resulted in the formation of the opposite trans diastereoisomer.

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Diastereoselective Temporary Silicon‐Tethered Ring‐Closing‐Metathesis Reactions with Prochiral Alcohols: A New Approach to Long‐Range Asymmetric Induction

2003

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“…[1,2] Despite limited generality, asymmetric strategies enabling such functionalizations have found important applications in target-oriented synthesis, thereby indicating their potential. [1,2] Despite limited generality, asymmetric strategies enabling such functionalizations have found important applications in target-oriented synthesis, thereby indicating their potential.…”

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confidence: 99%

“…Control of remote stereocenters constitutes an important challenge in modern organic synthesis. [1,2] Despite limited generality, asymmetric strategies enabling such functionalizations have found important applications in target-oriented synthesis, thereby indicating their potential. [1e, 2] In recent years, dienamine-and trienamine-mediated reactions have emerged as new tools that enable stereoselective functionalizations of unsaturated aldehydes at the remote g-or epositions, respectively.…”

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Enantioselective H‐Bond‐Directing Approach for Trienamine‐mediated Reactions in Asymmetric Synthesis

et al. 2012

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“…[1] The problem can be extended to remote sites which must be activated to ensure better reactivity. While most early examples of remote asymmetric inductions rely on enzyme catalysis or intramolecular relay of chiral information through the substrate, [2] current studies have demonstrated that chiral catalysts can facilitate enantioselectivity in variety of reactions.…”

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Trienamines Derived from Interrupted Cyclic 2,5‐Dienones: Remote δ,ε‐CC Bond Activation for Asymmetric Inverse‐Electron‐Demand Aza‐Diels–Alder Reaction

Feng

Zhou

et al. 2013

Angewandte Chemie

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A special challenge in the field of asymmetric catalysis is the realization of remote stereocontrol.[1] The problem can be extended to remote sites which must be activated to ensure better reactivity. While most early examples of remote asymmetric inductions rely on enzyme catalysis or intramolecular relay of chiral information through the substrate, [2] current studies have demonstrated that chiral catalysts can facilitate enantioselectivity in variety of reactions.[3] In particular, our group and the group of Jørgensen found that the well-established enamine chemistry of saturated carbonyl compounds could be expanded to polyconjugated 2,4-dienals based on the principle of vinylogy, [4] thus leading to the remote e-site activation and still allowing highly stereoselective cycloadditions at b,e-sites of in situ formed linear trienamine intermediates.[5] Moreover, such an activation mode was successfully applied to 2,4-dienone analogues. Unfortunately, it was not possible to utilize 2,4-dienones with an enolizable a'-alkyl substitution because the cross-conjugated trienamine species were preferably generated. [6] In fact, we also found that the cyclic 2,4-dienone 1 would predominantly generate the cross-conjugated trienamine I, catalyzed by a primary amine, and then react with a dienophile by a a',b-regioselective [4+2] annulation pathway (Scheme 1). [7] To overcome the inherent preference for the formation of cross-conjugated trienamines from 2,4-dienones bearing an enolizable a'-alkyl group, we envisaged that an appropriately positioned d,e-C=C bond, as shown for the interrupted 3-allyl cyclohexen-2-one 2 a (Scheme 1), would induce the generation of the desired polyconjugated linear trienamine II, rather than the dienamine [8] III which has a higher energy.[9] Thus, the electron-donating effects of the amine could be transmitted through the conjugated p system, and raise the HOMO energy of the remote d,e-C=C group to participate in asymmetric reactions.Based on the above considerations, we initially investigated the reaction of the 2,5-dienone 2 a and the 1-azadiene 3 a, containing a 1,2-benzoisothiazole-1,1-dioxide moiety, [10] in the presence of 9-amino-9-deoxyepiquinidine (C1) and benzoic acid (A1).[11] To our gratification, the reaction proceeded smoothly in toluene at 35 8C, and the inverse-electrondemand aza-Diels-Alder cycloaddition product 4 a was isolated in 63 % yield with exclusive d,e-regioselectivity.

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The control of remote asymmetric centres via reduction of acyclic carbonyl functions

Cited by 37 publications

References 117 publications

Diastereoselective Temporary Silicon‐Tethered Ring‐Closing‐Metathesis Reactions with Prochiral Alcohols: A New Approach to Long‐Range Asymmetric Induction

Diastereoselective Temporary Silicon‐Tethered Ring‐Closing‐Metathesis Reactions with Prochiral Alcohols: A New Approach to Long‐Range Asymmetric Induction

Enantioselective H‐Bond‐Directing Approach for Trienamine‐mediated Reactions in Asymmetric Synthesis

Trienamines Derived from Interrupted Cyclic 2,5‐Dienones: Remote δ,ε‐CC Bond Activation for Asymmetric Inverse‐Electron‐Demand Aza‐Diels–Alder Reaction

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