Pd-catalyzed cascade allylic alkylation and dearomatization reactions of indoles with vinyloxirane

Gao, Run‐Duo; Xu, Qing‐Long; Dai, Li‐Xin; You, Shu‐Li

doi:10.1039/c6ob01523a

Cited by 25 publications

(9 citation statements)

References 38 publications

(2 reference statements)

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“…Friedel-Crafts-type allylic alkylation and dearomatization of the indole affords the product. 81 Compounds 198 were obtained in very good yields in the presence of 2.5 equivalents of Et 3 B as promoter and 1 equivalent of MgSO 4 as additive in THF at 50 °C. Taking advantage of the nucleophilicity of C-3 of the indole, and applying the same reaction conditions on dimethyl (3-indolylmethyl)malonate 199, but increasing the amount of Pd catalyst to 4 mol% and chang-ing the ligand to 8.5 mol% dppb, the allylic dearomatization afforded the spiroindolenine derivatives 200 with satisfactory yields and moderate diastereoselectivity (Scheme 82).…”

Section: Review Synthesismentioning

confidence: 99%

Pd-Catalyzed Domino Reactions Involving Alkenes To Access Substituted Indole Derivatives

et al. 2020

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Palladium-catalyzed domino reactions are advanced tools in achieving various nitrogen-containing heterocycles in an efficient and economical manner due to the reduced number of steps in the process. This review highlights recent advances in domino processes aimed at the synthesis of indole derivatives and polycyclic systems containing the indole nucleus in intra/intra- or intra/intermolecular reactions. In particular, we consider domino processes that involve a double bond in a step of the sequence, which allow the issue of regioselectivity in the cyclization to be faced and overcome. The different sections in this review focus on the synthesis of the indole nucleus and functionalization of the scaffold starting from different substrates that have been identified as activated starting materials, which involve a halogenated moiety or unactivated unsaturated systems. In the former case, the reaction is under Pd(0) catalysis, and in the second case a Pd(II) catalytic species is required and then an oxidant is necessary to reconvert the Pd(0) into the active Pd(II) species. On the other hand, the second method has the advantage that it uses easy available and inexpensive substrates.1 Introduction2 Indole Scaffold Synthesis2.1 Activated Substrates2.2 Unactivated Substrates3 Functionalization of Indole Scaffold3.1 Activated Substrates3.2 Unactivated Substrates4 Conclusions

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Section: Review Synthesismentioning

confidence: 99%

Pd-Catalyzed Domino Reactions Involving Alkenes To Access Substituted Indole Derivatives

et al. 2020

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“…The product of the dearomatization reaction 200 and its precursor 198 (R=Cl) have the same polarity; therefore, for their separation, indolenine 200 was converted into the corresponding less polar indoline (54 %) (Scheme 52). [236] A synthetic scheme has been proposed that allows, along with annealing, also carrying out the spirolinking of the cyclopropane fragment to the cyclohex [a]indole backbone. Stirring the diketone 201 with 2 equiv.…”

Section: The Indole Dearomatization Strategy In the Synthesis Of Spirmentioning

confidence: 99%

Section: Syntheses Of Spiroheterocycles From 3‐alkylidene‐indol‐2‐onementioning

confidence: 99%

Advances in the Synthesis of Benzo‐Fused Spiro Nitrogen Heterocycles: New Approaches and Modification of Old Strategies

Гатауллин

2020

Helvetica Chimica Acta

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The review covers the results of studies published in the literature on the synthesis of spiro-linked heterocycles of the indole, quinoline, benzoxazine, benzothiazine, indenoquinoxaline, pyridopyrimidine, and acridine series. Possible approaches to the synthesis of spirocycles through a sequence of well-known Knoevenagel, Michael reactions, deamination cyclization of 1,2-dicarbonyl, CH-acid compounds, direct cycloaddition of activated olefins to isatins, 3-alkylideneindoles, 2-oxindoles, in situ generated azomethine ylides, indenoquinoxalines are analyzed. Attention is drawn to approaches to the preparation of spiro-fused compounds using reactions of intra-and intermolecular dearomatization of indoles. Recent advances in the synthesis of spiro-linked benzo heterocycles from derivatives of 2-olefin substituted anilines are summarized. The examples of the synthesis of spiro-fused heterocycles by means of metal complexes catalyzed decomposition of diazo compounds are given. Some syntheses of biologically active representatives are shown, as well as the use of transformations of spiroheterocycles in the preparation of other heterocycles.

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“…Next, further optimization of the reaction conditions was carried out using L1 (Table 1). Reactions in various solvents, such as DMF,C H 2 Cl 2 ,a nd THF,a fforded comparable yields and enantioselectivity albeit with lower 3a/4a ratios (entries 2-4), whereas MeOH and PhMe led to almost no reaction (entries [5][6]. Further evaluation of the concentration( entries 7-11) of 1a revealed that c = 0.2 mol L À1 was optimal in terms of yield (entry 8).…”

mentioning

confidence: 99%

“…[3,4,5] Recently,w er ealized the construction of fused indolenine skeletons in ac ascadef ashion. [6] In 2014, the Rawal group and we independently reported an intermolecular cascade dearomatization reactiono fi ndole-based bisnucleophiles with propargyl carbonate, leading to aseries of spiroindolenines andspiroindolines. Moderate enantioselectivity ( 77 % ee)w as achieved for limited substrates (Scheme1,reaction 1).…”

mentioning

confidence: 99%

Palladium(0)‐Catalyzed Intermolecular Asymmetric Cascade Dearomatization Reaction of Indoles with Propargyl Carbonate

Ding

Gao

You

2019

Chemistry A European J

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An intermolecular asymmetric cascade dearomatization reaction of indole derivatives with propargyl carbonate was developed. The challenges associated with both the chemoselectivity between the carbon and nitrogen nucleophile and the enantioselective control during the formation of an all‐carbon quaternary stereogenic center were well addressed by a Pd catalytic system derived from the Feringa ligand. A series of enantioenriched multiply substituted fused indolenines were provided in good yields (71–86 %) with excellent enantioselectivity (91–96 % ee) and chemoselectivity (3/4>19:1 in most cases).

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Pd-catalyzed cascade allylic alkylation and dearomatization reactions of indoles with vinyloxirane

Cited by 25 publications

References 38 publications

Pd-Catalyzed Domino Reactions Involving Alkenes To Access Substituted Indole Derivatives

Pd-Catalyzed Domino Reactions Involving Alkenes To Access Substituted Indole Derivatives

Advances in the Synthesis of Benzo‐Fused Spiro Nitrogen Heterocycles: New Approaches and Modification of Old Strategies

Palladium(0)‐Catalyzed Intermolecular Asymmetric Cascade Dearomatization Reaction of Indoles with Propargyl Carbonate

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