Iodine-Mediated α-Acetoxylation of 2,3-Disubstituted Indoles

Zaimoku, Hisaaki; Hatta, Takashi; Taniguchi, Tsuyoshi; Ishibashi, Hiroyuki

doi:10.1021/ol302983t

Cited by 40 publications

(24 citation statements)

References 33 publications

(16 reference statements)

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“…This is an oteworthy accomplishment since related reactions usually proceed with preferential CÀHbond functionalization at the 1-position. [3,15,16] However,s ubstrate degradation was observed as ar esult of background oxidation of the free indole core by the iodine(III) reagent 2.W hereas the Boc-protected substrate did not provide the desired amination product (entry 2), the N-methylated substrate 5a readily formed the amination product 6a in 71 %yield (entry 3). Theformation of asecond minor regioisomeric product was observed under these conditions,w hich could be suppressed by conducting the reaction at 40 8 8C, although at the expense of the yield (entry 4).…”

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confidence: 99%

An Electrophilic Bromine Redox Catalysis for the Synthesis of Indole Alkaloid Building Blocks by Selective Aliphatic C−H Amination

2018

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Anew homogeneous bromine(ÀI/I) redox catalysis is described, whichi sb ased on monomeric bromine(I) compounds containing transferable phthalimidato groups. These catalysts enable intermolecular CÀHa mination reactions at previously unaccessible aliphatic positions and thus enlarge the synthetic potential of direct C À Nb ond formation, including its application in the synthesis of alkaloid building blocks.T his aspect is demonstrated by an ew synthetic approach to aspidospermidine.Inaddition to the development of the catalyst system, the structures of the involved bromine(I) key catalysts were fully elucidated, including by X-ray analyses. Prof. Dr.K.MuÇiz ICREA Pg. LluísC ompanys 23, 08010 Barcelona (Spain) Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.Scheme 2. Synthesis of monomeric phthalimidato-bromenium catalysts 9a,b with defined BrÀNbonds. Scheme 3. Conditions for phthalimide deprotection (1), the retrosynthesis approach (2), and the unreactive neopentylic position (3).Figure 2. Bromine-catalyzed CÀHa mination:m echanistic context. Angewandte Chemie Communications 15893

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confidence: 99%

An Electrophilic Bromine Redox Catalysis for the Synthesis of Indole Alkaloid Building Blocks by Selective Aliphatic C−H Amination

2018

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“…1 : 1a-d, 1f-m, 2a, 2d-m, 3, 4. 6,8,15 Repesentative procedure for C-H functionalization of indole derivatives with hypervalent iodine reagent (Table 1-3, Table 4 …”

Section: Methodsmentioning

confidence: 99%

“…The combination of PhIO and TMSN 3 increased the yield of 7a to 43% (entry 5). The other substrates 1c-e gave 3-azide compounds 7c-e in 16-30 % yields (entries [6][7][8]. The position of the substituted azide group in 2 and 7 was determined by differential nOe and H-H cosy spectra ( Figure 2).…”

Section: -Azide Substituentmentioning

confidence: 99%

Hypervalent Iodine Mediated One-Pot C-H Functionalization at 2α- or 3α-Position of Indole Derivatives

Higuchi¹,

Kawasaki²,

Inaba³

et al. 2014

HETEROCYCLES

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The one-pot 2-and 3-functionalization of 2,3-disubstituted indoles using a hypervalent iodine reagent has been developed. The substitution at the 2-position of indoles took place using phenyliodinebis(trifluoroacetate) with oxygen and carbon nucleophiles in moderate yields. The combination of iodosobenzene and trimethylsilyl azide afforded 3-azide derivatives preferentially.The latter reaction was applied to other 2,3-disubstituted indoles.Recently, Ishibashi's group revealed the combination of phenyliodine diacetate (PIDA) and tetrabutylammonium iodide (TBAI) reacted with tetrahydrocarbazoles to give 2-acetoxy derivatives. 6 Alternatively, Du Bois and co-workers developed that the reaction of tetrahydrocarbazoles using imino  3 -iodanes with a rhodium catalyst affords 2-and 3-amino derivatives. 7Recently, we developed the concise 2-functionalization of indole derivatives using a thionium species generated from DMSO-TFAA (Scheme 1). 8

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“…[3,15,16] Verlust an Substrat wurde jedoch aufgrund der Hintergrundoxidation des freien Indols durch das Iod(III)-Reagens 2 beobachtet. [3,15,16] Verlust an Substrat wurde jedoch aufgrund der Hintergrundoxidation des freien Indols durch das Iod(III)-Reagens 2 beobachtet.…”

Section: Zuschriftenunclassified

Eine elektrophile Brom‐Redoxkatalyse zur Synthese von Alkaloidbausteinen durch selektive aliphatische C‐H‐Aminierung

2018

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Eine neue homogene Brom(ÀI/I)-Redoxkatalyse wird beschrieben, die auf monomeren Brom(I)-Verbindungen mit übertragbaren Phthalimidatogruppen basiert. Diese Katalysatoren ermçglichen intermolekulare C-H-Aminierungen an zuvor nicht zugänglichen aliphatischen Positionen und erweitern somit das Synthesepotenzial der direkten C-N-Bindungsbildung einschließlichi hrer Anwendung in der Synthese von Alkaloidbausteinen. Dieser Aspekt wird anhand eines neuen synthetischen Zugangs zu Aspidospermidin demonstriert. Neben der Katalyseentwicklung wurden die Strukturen der beteiligten Brom(I)-Schlüsselkatalysatoren vollständig, auch mit Rçntgenstrukturanalysen, aufgeklärt.Schema 2. Synthese von monomeren Phthalimidato-Bromenium-Katalysatoren 9a, b mit definierten Br-N-Bindungen.

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Iodine-Mediated α-Acetoxylation of 2,3-Disubstituted Indoles

Cited by 40 publications

References 33 publications

An Electrophilic Bromine Redox Catalysis for the Synthesis of Indole Alkaloid Building Blocks by Selective Aliphatic C−H Amination

An Electrophilic Bromine Redox Catalysis for the Synthesis of Indole Alkaloid Building Blocks by Selective Aliphatic C−H Amination

Hypervalent Iodine Mediated One-Pot C-H Functionalization at 2α- or 3α-Position of Indole Derivatives

Eine elektrophile Brom‐Redoxkatalyse zur Synthese von Alkaloidbausteinen durch selektive aliphatische C‐H‐Aminierung

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