Catalytic Asymmetric Intermolecular Stetter Reaction of Heterocyclic Aldehydes with Nitroalkenes: Backbone Fluorination Improves Selectivity

DiRocco, Daniel A.; Oberg, Kevin M.; Dalton, Derek M.; Rovis, Tomislav

doi:10.1021/ja904375q

Cited by 220 publications

(94 citation statements)

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“…Fluorinated N-heterocyclic carbenes are emerging as valuable organocatalysts and powerful ancillary ligands for transition-metal catalysed processes. [1] Pertinent examples include the triazolium Stetter catalyst reported by Rovis and co-workers (1) where the introduction of fluorine improves efficiency, [2] and the ruthenium metathesis catalyst disclosed by Grubbs et al (2) [3] in which a fluorine-metal interaction leads to a rate acceleration. In both cases, the fluorine atom that is inextricably linked to catalyst performance is vicinal to one of the flanking nitrogens of the NHC (Figure 1).…”

Section: Graphical Abstractmentioning

confidence: 99%

The fluorine-NHC gauche effect: a structural and computational study

et al. 2013

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Section: Graphical Abstractmentioning

confidence: 99%

The fluorine-NHC gauche effect: a structural and computational study

et al. 2013

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“…For many Stetter systems, tertiary amines perform as optimal bases for carbene generation (47,50,51). For this reason, we were encouraged that DABCO or quinuclidine would not only serve as nucleophilic "triggers" (48) to promote our imagined conjugate addition reaction but would also prove suitable bases to deprotonate triazolium salt precatalyst 4b and generate the active carbene species.…”

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confidence: 99%

Multicatalytic, asymmetric Michael/Stetter reaction of salicylaldehydes and activated alkynes

Filloux

Lathrop²,

Rovis³

2010

Proc. Natl. Acad. Sci. U.S.A.

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128

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We report the development of a multicatalytic, one-pot, asymmetric Michael/Stetter reaction between salicylaldehydes and electrondeficient alkynes. The cascade proceeds via amine-mediated Michael addition followed by an N-heterocyclic carbene-promoted intramolecular Stetter reaction. A variety of salicylaldehydes, doubly activated alkynes, and terminal, electrophilic allenes participate in a one-step or two-step protocol to give a variety of benzofuranone products in moderate to good yields and good to excellent enantioselectivities. The origin of enantioselectivity in the reaction is also explored; E∕Z geometry of the reaction intermediate as well as the presence of catalytic amounts of catechol additive are found to influence reaction enantioselectivity.catalysis | organic synthesis | tandem catalysis

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“…Nevertheless, using acylsilanes 87 (Scheme 16) and enones of type 98 in the presence of DBU (base), THF (solvent) and thiazolium salt 100 (catalyst), good yields are obtained for the intermolecular Stetter reaction [351]. An example of catalytic enantioselective intermolecular Stetter reaction is given in Scheme 52 [352,353]. Because aldehydes RCHO can also react with intermediates 81 and give products of benzoin homo-coupling, 81 must be more reactive toward 98 than RCHO for successful intermolecular Stetter reactions.…”

Section: The Stetter Reaction: Umpolung Of Aldehydementioning

confidence: 99%

Organocatalysis: Fundamentals and Comparisons to Metal and Enzyme Catalysis

et al. 2016

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Catalysis fulfills the promise that high-yielding chemical transformations will require little energy and produce no toxic waste. This message is carried by the study of the evolution of molecular catalysis of some of the most important reactions in organic chemistry. After reviewing the conceptual underpinnings of catalysis, we discuss the applications of different catalysts according to the mechanism of the reactions that they catalyze, including acyl group transfers, nucleophilic additions and substitutions, and C-C bond forming reactions that employ umpolung by nucleophilic additions to C=O and C=C double bonds. We highlight the utility of a broad range of organocatalysts other than compounds based on proline, the cinchona alkaloids and binaphthyls, which have been abundantly reviewed elsewhere. The focus is on organocatalysts, although a few examples employing metal complexes and enzymes are also included due to their significance. Classical Brønsted acids have evolved into electrophilic hands, the fingers of which are hydrogen donors (like enzymes) or other electrophilic moieties. Classical Lewis base catalysts have evolved into tridimensional, chiral nucleophiles that are N-(e.g., tertiary amines), P-(e.g., tertiary phosphines) and C-nucleophiles (e.g., N-heterocyclic carbenes). Many efficient organocatalysts bear electrophilic and nucleophilic moieties that interact simultaneously or not with both the electrophilic and nucleophilic reactants. A detailed understanding of the reaction mechanisms permits the design of better catalysts. Their construction represents a molecular science in itself, suggesting that sooner or later chemists will not only imitate Nature but be able to catalyze a much wider range of reactions with high chemo-, regio-, stereo-and enantioselectivity. Man-made organocatalysts are much smaller, cheaper and more stable than enzymes.

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Catalytic Asymmetric Intermolecular Stetter Reaction of Heterocyclic Aldehydes with Nitroalkenes: Backbone Fluorination Improves Selectivity

Cited by 220 publications

References 28 publications

The fluorine-NHC gauche effect: a structural and computational study

The fluorine-NHC gauche effect: a structural and computational study

Multicatalytic, asymmetric Michael/Stetter reaction of salicylaldehydes and activated alkynes

Organocatalysis: Fundamentals and Comparisons to Metal and Enzyme Catalysis

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