Organocatalytic Enantioselective Assembly of Spirooxindole‐naphthopyrans through Tandem Friedel–Crafts Type/Hemiketalization

Muthusamy, Subramaniam; Prakash, Muthuraj; Gromiha, M. Michael; Kesavan, Venkitasamy

doi:10.1002/cctc.201600087

Cited by 28 publications

(11 citation statements)

References 50 publications

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“…The chiral spirooxindole naphthopyran 115 was synthesized through an organocatalytic enantioselective Friedel‐Crafts type reaction/Michael addition, using the oxindole α‐keto ester 112 and 2‐naphthol 113 in the presence of a catalytic amount of chiral thiourea 114 (5 mol‐%) in trifluoromethylbenzene at room temperature for 24 h (Scheme ). The reaction furnished the adduct I followed by a cyclization reaction to form the hemiketal II which underwent dehydration with a catalytic amount of sulfuric acid to produce the spirooxindole naphthopyran 115 in 89 % yield and with high enantioselectivity (98 % ee).…”

Section: Asymmetric Synthesis Of Spirooxindoles In One Stepmentioning

confidence: 99%

Organocatalytic Synthesis of Chiral Spirooxindoles with Quaternary Stereogenic Centers

Sansinenea

Martínez

2020

Eur J Org Chem

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The structure of spirooxindoles is present in a large number of natural compounds, with relevant and different biological activities. The organic synthesis of these compounds has been a synthetic challenge due to the fusion of two or more cycles with one or more contiguous stereogenic centers. In this review, it has been described, the feasibility of organocatalytic asymmetric synthesis for the achievement of chiral spirooxindoles through two‐ or three‐component reaction in the presence of a chiral organocatalyst producing the compounds with high yield, high diastereoselectivity and with high enantiomeric purity. This review covers literature from 2010 to 2019. The most explored reactions for this purpose have been 1,3‐dipolar cycloaddition, Diels‐Alder and nucleophilic heterocyclic carbenes reactions, where their reaction mechanisms showed in this review are an approach of a possible mechanism.

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Section: Asymmetric Synthesis Of Spirooxindoles In One Stepmentioning

confidence: 99%

Organocatalytic Synthesis of Chiral Spirooxindoles with Quaternary Stereogenic Centers

Sansinenea

Martínez

2020

Eur J Org Chem

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“…The Kesavan group has published a straightforward synthesis of several oxindole-fused naphthopyran derivatives 60 by combining oxindole α-ketoester 29 and 2-naphthol 59 and using a sequence of Friedel-Crafts-hemiketalization reactions [ 47 ]. Under the optimized conditions (i.e .…”

Section: Thiourea-based Catalystsmentioning

confidence: 99%

Non-Covalent Organocatalyzed Domino Reactions Involving Oxindoles: Recent Advances

et al. 2017

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The ubiquitous presence of spirooxindole architectures with several functionalities and stereogenic centers in bioactive molecules has been appealing for the development of novel methodologies seeking their preparation in high yields and selectivities. Expansion and refinement in the field of asymmetric organocatalysis have made possible the development of straightforward strategies that address these two requisites. In this review, we illustrate the current state-of-the-art in the field of spirooxindole synthesis through the use of non-covalent organocatalysis. We aim to provide a concise overview of very recent methods that allow to the isolation of unique, densely and diversified spirocyclic oxindole derivatives with high structural diversity via the use of cascade, tandem and domino processes.

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“…It is worth mentioning that the two adjacent quaternary stereocenters present in the oxindole fused chroman‐3‐ol moiety at the C‐3 position make this moiety difficult to construct. A few methods comprising a tandem Friedel–Crafts‐type reaction of 2‐naphthol or cascade Michael‐addition of 8‐hydroxyquinoline have been targeted to accomplish the key chroman ring in spiro[chroman‐4,3′‐oxindole] (Scheme a). However, the development of a straightforward and sensible method to access such skeletons from simple starting materials is highly desirable for drug development.…”

Section: Figurementioning

confidence: 99%

Diastereoselective Intramolecular Aldol‐Type Trapping of Zwitterionic Intermediates by Ketones for the Synthesis of Spiro[chroman‐4,3′‐oxindole] Derivatives

et al. 2016

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As imple,m ild and efficientr hodium-catalyzed aromaticC -H functionalization of a-phenoxy ketones by 3-diazooxindolesf or the synthesis of the spiro[chroman-4,3'-oxindole] ring system is described. As eries of functionalized spiro[chroman-4,3'-oxindole] derivatives bearing twoa djacent quaternary carbon centers have been attained in ah ighly diastereoselectivem anner with very good yields.Control experiments suggested the possibility of an intramolecular aldol-type trapping of zwitterionic intermediates aftert he C-H functionalization. Furthermore,t he applicability of this method has been tested by ag ram-scale synthesis. Af acile treatment with base enabled the access to both synand anti-diastereomers via isomerization.

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Organocatalytic Enantioselective Assembly of Spirooxindole‐naphthopyrans through Tandem Friedel–Crafts Type/Hemiketalization

Cited by 28 publications

References 50 publications

Organocatalytic Synthesis of Chiral Spirooxindoles with Quaternary Stereogenic Centers

Organocatalytic Synthesis of Chiral Spirooxindoles with Quaternary Stereogenic Centers

Non-Covalent Organocatalyzed Domino Reactions Involving Oxindoles: Recent Advances

Diastereoselective Intramolecular Aldol‐Type Trapping of Zwitterionic Intermediates by Ketones for the Synthesis of Spiro[chroman‐4,3′‐oxindole] Derivatives

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