Design of a Combinational Magnesium Catalyst for the Stereocontrolled Cross Reaction of Enones

Yang, Dongxu; Wang, Linqing; Han, Fengxia; Zhao, Depeng; Wang, Rui

doi:10.1002/chem.201403183

Cited by 34 publications

(9 citation statements)

References 108 publications

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“…The following year, Wang et al designed a combinational magnesium catalyst for the stereocontrolled cross reaction of enones. 267 The stereocontrol of the reaction between 312 and 313 (Scheme 88) was particularly challenging, since the reaction partners have a very similar substitution pattern, but the use of the phosphoric acid L8, together with quinidine C12 and MgBu 2 in p-xylene was able to ensure the formation of γ,ipso-[4 + 2] cyclization products 314 in modest to good yields and high diastereo-and enantioselectivities. Nucleophilic enones 312 at first coordinate to the metal center of the preformed combinational catalyst (Scheme 88), that determines the attack direction to electrophilic enones 313.…”

Section: Vinylogous Ketonesmentioning

confidence: 99%

New Developments of the Principle of Vinylogy as Applied to π-Extended Enolate-Type Donor Systems

et al. 2020

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The principle of vinylogy states that the electronic effects of a functional group in a molecule are possibly transmitted to a distal position through interposed conjugated multiple bonds. As an emblematic case, the nucleophilic character of a π-extended enolate-type chain system may be relayed from the legitimate α-site to the vinylogous γ, ε, ..., ω remote carbon sites along the chain, provided that suitable HOMO-raising strategies are adopted to transform the unsaturated pronucleophilic precursors into the reactive polyenolate species. On the other hand, when “unnatural” carbonyl ipso -sites are activated as nucleophiles (umpolung), vinylogation extends the nucleophilic character to “unnatural” β, δ, ... remote sites. Merging the principle of vinylogy with activation modalities and concepts such as iminium ion/enamine organocatalysis, NHC-organocatalysis, cooperative organo/metal catalysis, bifunctional organocatalysis, dicyanoalkylidene activation, and organocascade reactions represents an impressive step forward for all vinylogous transformations. This review article celebrates this evolutionary progress, by collecting, comparing, and critically describing the achievements made over the nine year period 2010–2018, in the generation of vinylogous enolate-type donor substrates and their use in chemical synthesis.

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Section: Vinylogous Ketonesmentioning

confidence: 99%

New Developments of the Principle of Vinylogy as Applied to π-Extended Enolate-Type Donor Systems

et al. 2020

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“…Even with these challenges, direct, intermolecular [4+2] cycloadditions merging two α,β‐unsaturated carbonyls have been achieved with success, notably in the dienamine‐ or trienamine‐triggered catalytic modalities, where maximum selectivity was attained when the reactivity of the two reaction partners was properly differentiated 5–8. Despite these achievements, a truly viable and general approach to chemo‐ and stereoselectively merging two similarly reactive α,β‐unsaturated carbonyls remains elusive.…”

Section: Scope Of the Direct Amine‐catalyzed Vinylogous Asymmetric [4mentioning

confidence: 99%

Organocatalytic, Asymmetric Eliminative [4+2] Cycloaddition of Allylidene Malononitriles with Enals: Rapid Entry to Cyclohexadiene‐Embedding Linear and Angular Polycycles

et al. 2015

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A direct aminocatalytic synthesis has been developed for the chemo-, regio-, diastereo-, and enantioselective construction of densely substituted polycyclic carbaldehydes containing fused cyclohexadiene rings. The chemistry utilizes, for the first time, remotely enolizable π-extended allylidenemalononitriles as electron-rich 1,3-diene precursors in a direct eliminative [4+2] cycloaddition with both aromatic and aliphatic α,β-unsaturated aldehydes. The generality of the process is demonstrated by approaching 6,6-, 5,6-, 7,6-, 6,6,6-, and 6,5,6-fused ring systems, as well as biorelevant steroid-like 6,6,6,6,5- and 6,6,6,5,6-rings. A stepwise reaction mechanism for the key [4+2] addition is proposed as a domino bis-vinylogous Michael/Michael/retro-Michael reaction cascade. The utility of the malononitrile moiety as traceless activating group of the dicyano nucleophilic substrates is demonstrated.

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“…The strategy involved a bi-ligand system based on quinidine and MgBu 2 with a phosphoric acid as the second ligand (Scheme 45). 94 By developing this combinational magnesium system, the authors achieved a highly enantioselective [4 + 2] cyclization of enones. A series of poly-substituted six-membered rings were obtained with good enantioselectivities.…”

Section: Additives' Effects (Second Ligand) In the In Situ Magnesium Catalysismentioning

confidence: 99%

Magnesium Catalysis in Asymmetric Synthesis

Yang

Wang

et al. 2019

Chem

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In reviewing magnesium-catalyzed asymmetric reactions, we discuss the two general strategies for generating chiral organometallic Mg(II) complexes. Magnesium is one of the most abundant metals on earth and can be applied in a wide range of fundamental asymmetric reactions. However, compared with those of many other metals, the design and application of magnesium catalysts in asymmetric reactions are relatively limited. In this review, we provide insightful discussions of the catalytic strategies associated with Mg(II) catalysts, related mechanism considerations, and current limitations, as well as the opportunities associated with greater focus on magnesium catalysts in chemical synthesis.

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Design of a Combinational Magnesium Catalyst for the Stereocontrolled Cross Reaction of Enones

Cited by 34 publications

References 108 publications

New Developments of the Principle of Vinylogy as Applied to π-Extended Enolate-Type Donor Systems

New Developments of the Principle of Vinylogy as Applied to π-Extended Enolate-Type Donor Systems

Organocatalytic, Asymmetric Eliminative [4+2] Cycloaddition of Allylidene Malononitriles with Enals: Rapid Entry to Cyclohexadiene‐Embedding Linear and Angular Polycycles

Magnesium Catalysis in Asymmetric Synthesis

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