Inside Cover: Synthesis of Indolin‐3‐ones and Tetrahydro‐4‐quinolones from α‐Imino Esters (Asian J. Org. Chem. 2/2013)

Shimizu, Makoto; Takao, Yuki; Katsurayama, Haruna; Mizota, Isao

doi:10.1002/ajoc.201390004

Cited by 4 publications

(5 citation statements)

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“…Substitution of the cyanoaryl moiety with electron‐donating methoxy or methyl groups was well tolerated and the products 58 – 60 were isolated in moderate‐to‐good yields (43–66 %). Importantly, ketimines derived from phenyl‐ and indolylglyoxylate also underwent the cyclization reaction to form the 2‐methoxycarbonyl‐3‐iminoindolines 61 and 62 , respectively . For these ester‐substituted imines, it was empirically found that zinc gave better results (55 and 45 %) than manganese (26 and 30 %).…”

Section: Resultsmentioning

confidence: 99%

Development, Scope, and Applications of Titanium(III)‐Catalyzed Cyclizations to Aminated N‐Heterocycles

Leijendekker

Weweler

Leuther

et al. 2019

Chemistry A European J

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The exceptionally mild conditions of at itanium(III)-catalyzed cyclization reactionp aired with ac onvenient acid/base extraction have enabled the straightforward synthesis, isolation, and direct N-functionalization of amino heterocycles such as 3-aminoindoles and -pyrroles.T he unprotected heterocycles are ideal building blocks fort he installation of aminatedi ndoles and pyrroles into target molecules, but their sensitivity has previously impeded their synthesis by modernc atalytic methods. This full paper presents the development and extended scope of the new cyclization methodology.T he transformation of the products into fused bis-indoles is also demonstrated along with the discoveryo f an unusual palladium-catalyzed reductive biphenyl coupling reaction. The titanium(III)-catalyzed cyclization hasa lso been appliedt ot he synthesis of substituted 3-iminoindolines, which are of potential interestf or applicationsi nn atural product synthesis and exhibit tunable blue-to-green fluorescence properties.Supporting information and the ORCID identification number(s) for the author(s) of this articlecan be found under: https://doi.org/10.1002/chem.201805909.Scheme1.a) Usualand ideal scenarios for the catalytic synthesis of 3-aminoindole and -pyrrole building blocks. b) Envisionedtitanium(III)-catalyzed cyclization to furnish unprotected, electron-rich 3-aminoheterocycles.

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Section: Resultsmentioning

confidence: 99%

Development, Scope, and Applications of Titanium(III)‐Catalyzed Cyclizations to Aminated N‐Heterocycles

Leijendekker

Weweler

Leuther

et al. 2019

Chemistry A European J

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“…Following these conditions, the products 6 a – c were furnished in 43–66 % yield. To our delight, even an ester‐substituted imine 5 d that was prepared from methyl phenylglyoxylate underwent the cyclization to iminoindoline 6 d in 55 % yield …”

Section: Methodsmentioning

confidence: 96%

“…To our delight, even an ester-substituted imine Angewandte Chemie 5d that was prepared from methyl phenylglyoxylate underwent the cyclization to iminoindoline 6d in 55 %y ield. [19] Then, it was probed whether the cyclization products 2 could be directly submitted after the extraction to sequential modifications and couplings.Starting from imine 1a,adirect Boc-protection of the 3-amino group of the crude cyclization product was conveniently achieved with catalytic amounts of ZrCl 4 in 79 %o verall yield (7,S cheme 5). [20] In as imilar manner,a nN -acetylation with Ac 2 O, at osylation with tosyl chloride,a nd ap hthalimide formation using phthalic anhydride were achieved in good yields in as ingle reaction sequence (8-10).…”

Section: Methodsmentioning

confidence: 99%

Catalytic Reductive Synthesis and Direct Derivatization of Unprotected Aminoindoles, Aminopyrroles, and Iminoindolines

et al. 2017

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A titanium(III)-catalyzed radical cyclization to unprotected 3-aminoindoles, 3-aminopyrroles, or 3-iminoindolines is reported. The reaction is non-hazardous, scalable, and allows facile isolation of the free products by extraction. The method is demonstrated on a large substrate scope and it further allows the direct installation of various nitrogen protecting groups or the synthesis of building blocks for peptide chemistry in a single sequence. Fused bisindoles can be directly accessed from the cyclization products.

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“…We have been interested in the reactivity of aiminoesters in umpolung reactions, 5 and a facile indolin-3one synthesis via aza-Brook rearrangement has been developed (Scheme 1). 6 However, difficulties have been encountered regarding the substituents at the 2-position, i.e., only 2,2-disubstituted derivatives 2 could be synthesized by our previously reported procedure (compound 2, R ¼ Ar or CO 2 R 0 ).…”

Section: Introductionmentioning

confidence: 99%

A facile approach to 2-alkoxyindolin-3-one and its application to the synthesis of N-benzyl matemone

et al. 2019

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Inside Cover: Synthesis of Indolin‐3‐ones and Tetrahydro‐4‐quinolones from α‐Imino Esters (Asian J. Org. Chem. 2/2013)

Cited by 4 publications

References 0 publications

Development, Scope, and Applications of Titanium(III)‐Catalyzed Cyclizations to Aminated N‐Heterocycles

Development, Scope, and Applications of Titanium(III)‐Catalyzed Cyclizations to Aminated N‐Heterocycles

Catalytic Reductive Synthesis and Direct Derivatization of Unprotected Aminoindoles, Aminopyrroles, and Iminoindolines

A facile approach to 2-alkoxyindolin-3-one and its application to the synthesis of N-benzyl matemone

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