Novel Iminium Compounds from N-Alkylanilinium Perchlorates and Aldehydes and Their Unexpected (Domino Type) Reactions

Westerwelle, Ulrich; Keuper, Ralf; Risch, Nikolaus

doi:10.1021/jo00112a058

Cited by 16 publications

(10 citation statements)

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“…d Gibbs free energies in kcal/mol for homolytic cleavage determined by eq 17. The corresponding BDE values were taken from ref b. e Reversible oxidation potentials of the radicals in volts vs Fc/Fc + .…”

Section: Resultsmentioning

confidence: 99%

Hydride Affinities of Arylcarbenium Ions and Iminium Ions in Dimethyl Sulfoxide and Acetonitrile

1998

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Gibbs free energies for scission of C−H bonds leading to carbanion and proton (mode a), radical pair (mode b), and carbenium ion and hydride (mode c) have been determined for a series of acidic C−H bonds in ca. 45 weak acids. This involved the use of the equilibrium acidities (or homolytic bond dissociation enthalpies), redox potentials in DMSO or MeCN solution, and the appropriate thermodynamic cycles in the two solvents. The introduction of electron-donating groups generally results in small-to-negligible effects on ΔG R - values (mode a scission) but in a relatively large stabilizing influence on the ΔG R + values for heterolytic cleavage to hydride and carbenium ion (mode c). Electron-withdrawing groups exert large stabilizing effects on ΔG R − , but their effects on ΔG R + are dependent on the nature of the substituents. The heterolytic processes a are usually favored in solution due to the strong solvation of the proton. Homolytic scission (mode b) is usually more favorable than the corresponding heterolytic process c, but they can be comparable when strong electron-donating groups such as dialkylamino are present. Indeed, heterolytic cleavage to hydride and carbenium ion was ca. 10 kcal/mol more favorable than homolytic cleavage for a series of highly stabilized 2-benzoyl-N,N‘-dialkylperhydropyrimidines.

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Section: Resultsmentioning

confidence: 99%

Hydride Affinities of Arylcarbenium Ions and Iminium Ions in Dimethyl Sulfoxide and Acetonitrile

1998

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“…It is worth noting that the competitive isomerization of the in situ formed aliphatic N-arylimines to the corresponding enamines and/or the partial isomerization of 6 b were never observed. [22,23] This catalytic process was also compatible with a,b-unsaturated aldehydes (entry 5), electron-neutral, -rich, and -poor aromatic aldehydes (entries 6-10), and heteroaromatic aldehydes (entry 11), affording the corresponding products 7 g-7 m in similarly good yields (57-83 %), high diastereoselectivities (d.r. > 9:1), and excellent enantioselectivities (84-98 % ee).…”

mentioning

confidence: 81%

Chiral Phosphoric Acid‐Catalyzed Enantioselective Three‐Component Povarov Reaction Using Cyclic Enethioureas as Dienophiles: Stereocontrolled Access to Enantioenriched Hexahydropyrroloquinolines

Dagousset

Retailleau

Masson

et al. 2012

Chemistry A European J

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“…The intricacies of iodine catalysis in the context of organic reactions remain poorly understood; most reports do not consider the role of the oxidant or the mechanism of oxidation. Most describe the oxidation simply as “spontaneous” [5,16,31–37] …”

Section: Entry Catalyst Atm Additive Yield (5/6 A)[a]mentioning

confidence: 99%

“…The critical iminium cation IV is generated from condensation of the aniline ( I ) and α,ω‐aryl aldehyde II . The desired pathway follows a Kozlov‐type cyclocondensation of the imine with the enol tautomer of the second aldehyde [13,37] . That reaction may be stepwise or concerted: similar inverse electron‐demand Diels‐Alder reactions are well‐precedented [55–57] .…”

Section: Entry Catalyst Atm Additive Yield (5/6 A)[a]mentioning

confidence: 99%

Optimizing the Iodide/Iodonium/O₂ Oxidation Cycle Enhances the Scope, Selectivity, and Yields of Hydroiodic Acid‐Catalyzed Multicomponent Cyclocondensation Reactions

et al. 2021

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Catalytic iodine in the presence of water acts indirectly as a source of Brønsted acid and, concurrently, generates iodonium ion and hydrogen peroxide, which mediate the final oxidative aromatization step in the multicomponent cyclocondensation of an aromatic amine and two aliphatic aldehyde compounds. The oxidative cycle in this and related iodine‐catalyzed reactions is seldom discussed, generally unoptimized, and rarely investigated in detail. This work establishes that two independent catalytic cycles (H+ and I−/I+) drive such multicomponent cyclocondensation/ oxidation reactions, provided that the oxidant is generated in sufficient concentration to inhibit oxidation of the dihydroquinoline by the intermediate iminium cation. The complementary dual catalytic cycles, when optimized, act in concert to suppress side product formation, which simplifies isolation and purification of the self‐aggregating products, and increases the efficiency and scope of the Wang‐Kozlov multicomponent reaction.

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Novel Iminium Compounds from N-Alkylanilinium Perchlorates and Aldehydes and Their Unexpected (Domino Type) Reactions

Cited by 16 publications

References 0 publications

Hydride Affinities of Arylcarbenium Ions and Iminium Ions in Dimethyl Sulfoxide and Acetonitrile

Hydride Affinities of Arylcarbenium Ions and Iminium Ions in Dimethyl Sulfoxide and Acetonitrile

Chiral Phosphoric Acid‐Catalyzed Enantioselective Three‐Component Povarov Reaction Using Cyclic Enethioureas as Dienophiles: Stereocontrolled Access to Enantioenriched Hexahydropyrroloquinolines

Optimizing the Iodide/Iodonium/O₂ Oxidation Cycle Enhances the Scope, Selectivity, and Yields of Hydroiodic Acid‐Catalyzed Multicomponent Cyclocondensation Reactions

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Novel Iminium Compounds from N-Alkylanilinium Perchlorates and Aldehydes and Their Unexpected (Domino Type) Reactions

Cited by 16 publications

References 0 publications

Hydride Affinities of Arylcarbenium Ions and Iminium Ions in Dimethyl Sulfoxide and Acetonitrile

Hydride Affinities of Arylcarbenium Ions and Iminium Ions in Dimethyl Sulfoxide and Acetonitrile

Chiral Phosphoric Acid‐Catalyzed Enantioselective Three‐Component Povarov Reaction Using Cyclic Enethioureas as Dienophiles: Stereocontrolled Access to Enantioenriched Hexahydropyrroloquinolines

Optimizing the Iodide/Iodonium/O2 Oxidation Cycle Enhances the Scope, Selectivity, and Yields of Hydroiodic Acid‐Catalyzed Multicomponent Cyclocondensation Reactions

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Optimizing the Iodide/Iodonium/O₂ Oxidation Cycle Enhances the Scope, Selectivity, and Yields of Hydroiodic Acid‐Catalyzed Multicomponent Cyclocondensation Reactions