Thionium-Based One-Pot Construction of Homo-/Heterodimeric Pyrroloindoline from Tryptamine

Tayu, Masanori; Higuchi, Kazuhiro; Ishizaki, Takako; Kawasaki, Tomomi

doi:10.1021/ol5012373

Cited by 53 publications

(22 citation statements)

References 42 publications

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“…Recently, we34353637383940 and others41424344454647484950515253545556 reported the metal-free, sulfoxide directed57 C–H functionalization of a variety of molecular scaffolds, which was enabled by an interrupted Pummerer reaction28. Spurred on by these recent achievements, we considered the use of benzothiophene S -oxides 1 for the synthesis of important C3-functionalized benzothiophenes, as the corresponding sulfonium salts I and II , formed after reaction with the coupling partners, lack aromaticity about the five-membered ring and should therefore undergo facile C–C bond formation via [3,3]-sigmatropic rearrangement58, thus delivering unexplored reactivity not accessible in benzothiophenes.…”

Section: Resultsmentioning

confidence: 99%

Regioselective synthesis of C3 alkylated and arylated benzothiophenes

et al. 2017

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Benzothiophenes are heterocyclic constituents of important molecules relevant to society, including those with the potential to meet modern medical challenges. The construction of molecules would be vastly more efficient if carbon–hydrogen bonds, found in all organic molecules, can be directly converted into carbon–carbon bonds. In the case of elaborating benzothiophenes, functionalization of carbon–hydrogen bonds at carbon-number 3 (C3) is markedly more demanding than at C2 due to issues of regioselectivity (C3 versus C2), and the requirement of high temperatures, precious metals and the installation of superfluous directing groups. Herein, we demonstrate that synthetically unexplored but readily accessible benzothiophene S-oxides serve as novel precursors for C3-functionalized benzothiophenes. Employing an interrupted Pummerer reaction to capture and then deliver phenol and silane coupling partners, we have discovered a directing group-free method that delivers C3-arylated and -alkylated benzothiophenes with complete regioselectivity, under metal-free and mild conditions.

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Section: Resultsmentioning

confidence: 99%

Regioselective synthesis of C3 alkylated and arylated benzothiophenes

et al. 2017

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“…Higuchi and Kawasaki reported an interesting C2a À H functionalization of indoles directed by DMSO (Scheme 33). [51] Once DMSO has been activated with TFAA, it reacts through the cationic sulfur center with the 3-position of the indole to form 82.T automerization allows nucleophiles to attack in an S N 2' fashion at the C2a position of 83.V arious alkyl metal reagents as well as heteroatom-based nucleophiles were efficient coupling partners.A st he sulfur moiety is not retained in the product 84,the sulfoxide acts as at raceless directing group,w hich constitutes an ingenious approach to the activation of an unreactive C À Hb ond using asulfoxide.…”

Section: Reviewsmentioning

confidence: 99%

C−H Coupling Reactions Directed by Sulfoxides: Teaching an Old Functional Group New Tricks

2016

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Sulfoxides are classical functional groups for directing the stoichiometric metalation and functionalization of C-H bonds. In recent times, sulfoxides have been given a new lease on life owing to the development of modern synthetic methods that have arisen because of their unique reactivity. They have recently been used in catalytic C-H activation proceeding via coordination of an internal sulfoxide to a metal or through the action of an external sulfoxide ligand. Furthermore, sulfoxides are able to capture nucleophiles and electrophiles to give sulfonium salts, which subsequently enable the formation of C-C bonds at the expense of C-H bonds. This Review summarizes a renaissance period in the application of sulfoxides arising from their versatility in directing C-H functionalization.

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“…[19] Overman et al [20] have enantioselectively established the quaternary stereocenters using two intramolecular double Heck or dialkylation reactions. Very recently, Kawasaki et al [25] described a thionium-based one-pot synthesis of homo-/heterodimeric pyrroloindoline from the protected tryptamine. [21] Movassaghi et al [22] developed a cobaltmediated reductive homodimerization of 3a-bromopyrroloindolines that has been utilized by several groups to synthesize related 3a,3a'-bispyrrolidinoindoline alkaloids.…”

Section: Biomimetic Synthesis Of 3a3a'-bispyrrolidinoindoline Alkaloidsmentioning

confidence: 99%

Recent Advances of Transition Metal‐Mediated Oxidative Radical Reactions in Total Synthesis of Indole Alkaloids

Liang

Xia

2017

Chin. J. Chem.

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Over the past decades, transition metal-mediated oxidative radical reactions have been discovered and developed as a robust and conceptually novel approach for organic synthesis. This mini-review details the background, recent advances, and synthetic applications of transition metal-mediated oxidative radical reactions in indole alkaloids biomimetic synthesis. The organization of each section is based on the kind of indole alkaloids.

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Thionium-Based One-Pot Construction of Homo-/Heterodimeric Pyrroloindoline from Tryptamine

Cited by 53 publications

References 42 publications

Regioselective synthesis of C3 alkylated and arylated benzothiophenes

Regioselective synthesis of C3 alkylated and arylated benzothiophenes

C−H Coupling Reactions Directed by Sulfoxides: Teaching an Old Functional Group New Tricks

Recent Advances of Transition Metal‐Mediated Oxidative Radical Reactions in Total Synthesis of Indole Alkaloids

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