PdCl2‐Catalyzed Domino Reactions of 2‐Alkynylbenzaldehydes with Indoles: Synthesis of Fluorescent 5H‐Benzo[b]carbazol‐6‐yl Ketones

Tang, Ri‐Yuan; Li, Jin‐Heng

doi:10.1002/chem.201000133

Cited by 77 publications

(3 citation statements)

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“…Indole rings are electron-rich and therefore, they can also act as good nucleophiles to react with o -alkynylaryl aldehydes. Recently, Li and our group reported Pd(II)-catalyzed tandem reactions of o -alkynylaryl aldehydes with indoles. In the above reactions, the alkynes tethered to the aryl aldehydes were substituted by aryl or alkyl groups on another side, and a 6-endo-dig cyclization was realized to give 1 H -isochromenes (eq 1).…”

mentioning

confidence: 99%

Synthesis of Indole-Substituted Indanones via Palladium(II)-Catalyzed Tandem Reaction of ortho-Electron-Deficient Alkynyl-Substituted Aryl Aldehydes with Indoles

Zhang

Han

2016

Org. Lett.

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confidence: 99%

Synthesis of Indole-Substituted Indanones via Palladium(II)-Catalyzed Tandem Reaction of ortho-Electron-Deficient Alkynyl-Substituted Aryl Aldehydes with Indoles

Zhang

Han

2016

Org. Lett.

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“…And recently, (hetero)aromatics also can be used as good external nuclophiles. [87][88][89][90] Nevertheless, their asymmetric version remains underdeveloped. Thus far, the reported asymmetric nucleophilic addition of isobenzopyrylium has been limited only to the addition of alcohols and activated methylene compounds.…”

Section: Asymmetric Nucleophilic Additionmentioning

confidence: 99%

Asymmetric reactions involving isobenzopyrylium ion intermediates

Lan¹,

Yu²,

Qian³

et al. 2021

Arkivoc

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Isobenzopyrylium ions are highly reactive intermediates which have wide applications in synthetic chemistry. A range of catalytic reactions based on isobenzopyrylium, such as 1,2-nucleophilic addition, [4+2] and [3+2] cycloaddition provide a powerful protocol for constructing complex natural and unnatural products. Their asymmetric variations have been less explored, possibly owing to the lack of coordination sites within their planar structures. This mini-review summarizes the asymmetric transformations developed involving isobenzopyrylium ion intermediates. These works are arranged according to the reaction types. The catalytic systems and reaction mechanisms are described.

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“…In addition to the above concerns about the CÀXc leavage mechanism (Scheme 2), it is interesting to find that, despite the lower catalytic efficiency in the case of thioacetals, the PtCl 2 -catalyzed reactions of A and B would lead to the same products as those from the Pd catalysis, which implies that both Pd-and Pt-catalyzed reactions follow as imilar reaction pathway. [18] PtCl 2 is known to be aversatile catalyst for the activation of various p-systems, [4,19] and such an activationm ode was also observed in the reactions of aryl alkynep recursors bearingaslightly different o-substituent. [20] As shown in Equation (2), when one methoxy group of acetal A is replaced by an allyl group in F,Y amamoto and co-workers foundt hat the Pt-catalyzedb enzylic CÀHa ctivation could be realized via a [ 1,5]-hydrogen shift of Pt-vinylidene intermediate IN5 formed initially from the Pt-activated terminal alkyne.…”

Section: Introductionmentioning

confidence: 96%

Mechanistic Understanding of the Divergent Cyclizations of o‐Alkynylbenzaldehyde Acetals and Thioacetals Catalyzed by Metal Halides

Zhou

Wang

et al. 2015

Chemistry A European J

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The mechanisms of regiodivergent cyclizations of o-alkynylbenzaldehyde acetals and thioacetals catalyzed by Pd and Pt halides are studied. DFT calculations found that both reactions are initiated by electrophilic activation of the acetylenic moiety instead of the previously proposed metal-triggered CX (X=O, S) cleavage. Both the regioselective cyclization of the π-alkyne complex and the chemoselective [1,2]-migration in the carbenoid intermediate were determined as key steps to achieving the observed divergence. For acetal derivatives containing an internal alkyne, the 6-endo-dig cyclization is more favorable and leads to the carbenoid intermediate easily through further steps of CX fragmentation and carbocation cyclization. Then, from the carbenoid intermediate, the [1,2]-migration of sulfur is easier than that of H, Me, and Ph; whereas, a reversed aptitude was predicted for the oxygen analogue, which is consistent with the greater ability of sulfur atoms to stabilize β-carbocations. However, for precursors containing a terminal alkyne, the 5-exo-dig pathway is preferred and only the 1,2-disubstituted indene product is seen, irrespective of the nature of the acetal; thus, a different product from that reported in the literature is predicted for benzaldehyde acetal with a terminal alkyne at the ortho position. This prediction led us to reconsider some of the reported results and hidden realities were uncovered with solid new experimental evidence.

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PdCl₂‐Catalyzed Domino Reactions of 2‐Alkynylbenzaldehydes with Indoles: Synthesis of Fluorescent 5H‐Benzo[b]carbazol‐6‐yl Ketones

Cited by 77 publications

References 61 publications

Synthesis of Indole-Substituted Indanones via Palladium(II)-Catalyzed Tandem Reaction of ortho-Electron-Deficient Alkynyl-Substituted Aryl Aldehydes with Indoles

Synthesis of Indole-Substituted Indanones via Palladium(II)-Catalyzed Tandem Reaction of ortho-Electron-Deficient Alkynyl-Substituted Aryl Aldehydes with Indoles

Asymmetric reactions involving isobenzopyrylium ion intermediates

Mechanistic Understanding of the Divergent Cyclizations of o‐Alkynylbenzaldehyde Acetals and Thioacetals Catalyzed by Metal Halides

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