Chiral Brønsted acid catalyzed Friedel–Crafts alkylation reactions

You, Shu‐Li; Cai, Quan; Zeng, Mi

doi:10.1039/b817310a

Cited by 725 publications

(139 citation statements)

References 57 publications

Supporting

Mentioning

136

Contrasting

Unclassified

Order By: Relevance

“…[58] Ihre wohlbekannten Nachteile haben jedoch die Entwicklung alternativer, übergangsmetallkatalysierter C-HAlkylierungsmethoden, wie direkten Alkylierungen, [59,60] dehydrierenden Kupplungen [61] oder Olefin-Hydroarylierungen, [62] bewirkt. Ein wertvolles Beispiel, das in diesem Zusammenhang hervorgehoben werden soll, ist die von Michael et al entwickelte Carboaminierung.…”

Section: Alkylierung Einfacher Areneunclassified

Ohne dirigierende Gruppen: übergangsmetallkatalysierte C‐H‐Aktivierung einfacher Arene

et al. 2012

View full text Add to dashboard Cite

Der Einsatz von koordinierenden Gruppen als dirigierende Gruppen ist eine zuverlässige Methode zur Kontrolle von Reaktivität und Selektivität bei der Aktivierung von Aryl‐C‐H‐Bindungen. Im Hinblick auf die Anwendbarkeit von C‐H‐Aktivierungen in der Synthese besteht derzeit ein großes Interesse daran, Reaktionen zu entwickeln, in denen völlig auf dirigierende Gruppen verzichtet werden kann und somit die Funktionalisierung einfacher Benzolderivate möglich wird. Dieser Ansatz erfordert jedoch neue Strategien zur Reaktivitäts‐ und Selektivitätskontrolle. In diesem Kurzaufsatz werden aktuelle Fortschritte in dem noch jungen Gebiet der nicht‐chelatvermittelten C‐H‐Aktivierung diskutiert, wobei einige inspirierende Beispiele zur Reaktivitäts‐ und Selektivitätsinduktion hervorgehoben werden.

show abstract

Section: Alkylierung Einfacher Areneunclassified

Ohne dirigierende Gruppen: übergangsmetallkatalysierte C‐H‐Aktivierung einfacher Arene

et al. 2012

View full text Add to dashboard Cite

show abstract

“…In 2015, Han group reported the asymmetric syntheses of traditionally inaccessible P-stereogenic phosphinamides via Pd-catalyzed enantioselective C(sp 2 )-H functionalization (Scheme 18) [77]. It is well known that chiral phosphorus compounds play important roles as ligands or organocatalysts in asymmetric synthesis [73][74][75][76]. In 2015, Han group reported the asymmetric syntheses of traditionally inaccessible P-stereogenic phosphinamides via Pd-catalyzed enantioselective C(sp 2 )-H functionalization (Scheme 18) [77].…”

Section: Scheme 14mentioning

confidence: 99%

Advances in Enantioselective C–H Activation/Mizoroki-Heck Reaction and Suzuki Reaction

et al. 2018

View full text Add to dashboard Cite

Abstract:Traditional cross-coupling reactions, like Mizoroki-Heck Reaction and Suzuki Reaction, have revolutionized organic chemistry and are widely applied in modern organic synthesis. With the rapid development of C-H activation and asymmetric catalysis in recent years, enantioselective C-H activation/cross-coupling reactions have drawn much attention from researchers. This review summarizes recent advances in enantioselective C-H activation/Mizoroki-Heck Reaction and Suzuki Reaction, with emphasis on the structures and functions of chiral ligands utilized in different reactions.

show abstract

“…[2] Not surprisingly, the majority of studies in this field have been focused on the Friedel-Crafts reaction of indoles with a range of electrophiles. [3] Indeed, even C3-substituted indoles demonstrate high nucleophilicity; [4] C3-selective reactions have been realized by means of electrophilic compounds and subsequent tandem addition to the newly formed imine group. This processes lead to the construction of fused indolines having C3-quaternary stereocenters.…”

mentioning

confidence: 99%

“…Because a number of catalytic asymmetric reactions for the synthesis of C3-functionalized chiral indole derivatives have been well-established over the past years, [3] more enantioenriched indole precursors that might be utilized in the Lewis acid catalyzed imino-ene reaction could be accessed. For example, the asymmetric C3-selective FriedelCrafts reaction of indole with benzylideneacetone was easily conducted to give chiral intermediate 6, [17] which could be transformed into alkene precursors through the traditional Wittig reaction.…”

mentioning

confidence: 99%

Lewis Acid Catalyzed Intramolecular Direct Ene Reaction of Indoles

et al. 2010

View full text Add to dashboard Cite

Synthetic modifications on indole skeletons have provoked increasing interest because the related heterocyclic systems are present in numerous alkaloid products, pharmaceuticals, and agrochemicals.[1] Indole heterocycles, which basically consist of a benzo [b]pyrrole framework, are considered electron-rich compounds that exhibit substantial reactivity, especially at the C3-position.[2] Not surprisingly, the majority of studies in this field have been focused on the Friedel-Crafts reaction of indoles with a range of electrophiles.[3] Indeed, even C3-substituted indoles demonstrate high nucleophilicity;[4] C3-selective reactions have been realized by means of electrophilic compounds and subsequent tandem addition to the newly formed imine group. This processes lead to the construction of fused indolines having C3-quaternary stereocenters. In addition, C3-substituted indoles also show reactivity at the C2-position, [5] and the most well-established reaction is the Pictet-Spengler reaction.[6] On the other hand, the heteroaromatic indolyl structure contains an enamine functionality, which is likely to isomerize to an electrophilic imine (or iminium) group through proton transfer under the proper reaction conditions (such as by the activation of Brønsted or Lewis acids).[7] As a consequence, a chemoselective, direct nucleophilic C2-functionalization pathway could be developed for the synthesis of indoline compounds, as proposed in Equation (1; Nu = nucleophile). Nevertheless, such a synthetic approach has not yet been addressed.Recently, our research group [8] has reported an a-regioand stereoselective Michael addition of g,g-disubstituted a,bunsaturated aldehydes to nitroolefins through dienamine catalysis.[9] We further found that this activation mode was quite successful in the direct asymmetric alkylation reaction of 3-indolylmethanols [10] and g,g-disubstituted a,b-unsaturated aldehydes. As shown in Scheme 1, under the catalysis of a,a-diphenylprolinol O-TMS ether 1 (5 mol %) and AcOH (10 mol %), the exclusive a-regioselective alkylation product 4 a could be smoothly isolated in a diastereomerically pure form from 3-indolylphenylmethanol 2 a and 4-methyl-2-pentenal 3 a after reduction with NaBH 4 , and the reaction also gave excellent enantioselectivity. [11] In an attempt to conduct Friedel-Crafts annulation of 4 a under the catalysis of a Lewis acid such as AlCl 3 (1.0 equiv), we discovered that an unexpected and highly substituted cyclopentyl[b]indoline [12] compound 5 a could be cleanly obtained with complete diastereocontrol within 30 minutes, [13,14] while the FriedelCrafts product A was not detected (Scheme 1).[15] We recognized that an unprecedented and unique intramolecular imino-ene reaction of the indole heterocycle had occurredprobably through AlCl 3 -promoted enamine-imine isomerization and a subsequent ene cyclization (Scheme 1; intermediate B). The efficient participation of the inactivated imine in the relatively less explored imino-ene-type reaction was an unusual result. [16] To gain some insigh...

show abstract

Chiral Brønsted acid catalyzed Friedel–Crafts alkylation reactions

Cited by 725 publications

References 57 publications

Ohne dirigierende Gruppen: übergangsmetallkatalysierte C‐H‐Aktivierung einfacher Arene

Ohne dirigierende Gruppen: übergangsmetallkatalysierte C‐H‐Aktivierung einfacher Arene

Advances in Enantioselective C–H Activation/Mizoroki-Heck Reaction and Suzuki Reaction

Lewis Acid Catalyzed Intramolecular Direct Ene Reaction of Indoles

Contact Info

Product

Resources

About