Stereoselective synthesis of 2,3-disubstituted indoline, pyrrolidine and cyclic ether-fused 1,2-dihydroquinoline derivatives using alkyne iminium ion cyclization of vinylogous carbamates: switch of regioselectivity using an internal hydroxy group as a nucleophile

Gharpure, Santosh J.; Prasath, V.; Kumar, V. Senthil

doi:10.1039/c5cc05292k

Cited by 34 publications

(12 citation statements)

References 43 publications

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“…[128] trans-2,3-Disubstituted indolines 85 were stereoselectively constructed using an intramolecular, alkyne iminium ion cyclization of vinylogous carbamates derived from orthoalkynyl anilines and N-protected homopropargyl amines (Table 4, entry 5). [129] The phenol-ene reaction proved to be effective for the direct synthesis of substituted indolines 86 using N-mesyl-1,3-diynamines as substrates (Table 4, entry 6). [130] Additional Diels-Alder route was also applied to the preparation of 4,6-substituted-N-Ac-indolines 87 using N-homopropargyl-6dichloropyrones as substrates (Table 4, entry 7).…”

Section: Transition Metal-free Synthesis Of Indolinesmentioning

confidence: 99%

“…The use of silica gel to mediate the hydroamination/semipinacol rearrangement of 2‐alkylaminophenylpropynols was described for the synthesis of 2‐oxoindolines 84 (Table 4, entry 4) [128] . trans ‐2,3‐Disubstituted indolines 85 were stereoselectively constructed using an intramolecular, alkyne iminium ion cyclization of vinylogous carbamates derived from ortho ‐alkynyl anilines and N ‐protected homopropargyl amines (Table 4, entry 5) [129] . The phenol‐ene reaction proved to be effective for the direct synthesis of substituted indolines 86 using N ‐mesyl‐1,3‐diynamines as substrates (Table 4, entry 6) [130] .…”

Section: Synthesis Of Indolinesmentioning

confidence: 99%

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Recent Developments in the Cyclization of Alkynes and Nitrogen Compounds for the Synthesis of Indole Derivatives

Neto

Zeni

2021

Asian J Org Chem

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This review is intended to highlight the most useful approaches for the synthesis of indole derivatives (azaindoles, carbazoles, carbolines, indazoles, 3H-indoles, indolines, indolizines, isoindoles, and isoindolines), which were described by using transition-metal catalyzed cyclization reactions of alkynes and nitrogen compounds. The methodologies carried out under metal-free conditions will also be illustrated herein. This review will cover the data published mostly in the past decade. Synthesis of 6-AzaindolesAzaindoles, although rare in nature, have attracted a significant attention because some synthetic structures containing this nucleus exhibit biological activities. [17] The synthetic methods describing the preparation of azaindoles are limited. Usually their synthesis was achieved from the cyclization reaction of substrates containing aminopyridines. [18] Transition Metal-Free Synthesis of 6-AzaindolesWe have nominated two methodologies for the preparation of 6-azaindoles, which were developed using alkynes and nitrogen compounds in a metal-free protocol. In the first, an electrophilic cyclization condition, using iodine as an electrophilic source, was applied to 2-(azidomethyl)-3-alkynyl-pyrroles in the preparation of 4-iodo-6-azaindoles 1 (Scheme 1, eq 1). [19] The second approach described the preparation of 2,5-disubstituted 6azaindoles 2 from base-catalyzed intramolecular cyclization of 2-(azidomethyl)-3-alkynyl-pyrroles (Scheme 1, eq 2). [20] 3. Synthesis of 7-Azaindoles Transition Metal-Catalyzed Synthesis of 7-Azaindoles Silver-Catalyzed Synthesis of 7-AzaindolesSilver-catalyzed cyclization reactions of alkynes constitute powerful strategies for the construction of heterocycles. In particular, the 7-azaindoles could be obtained by these approaches. A general method for the preparation of aryl-[a] Dr. J.

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Section: Transition Metal-free Synthesis Of Indolinesmentioning

confidence: 99%

Section: Synthesis Of Indolinesmentioning

confidence: 99%

Recent Developments in the Cyclization of Alkynes and Nitrogen Compounds for the Synthesis of Indole Derivatives

Neto

Zeni

2021

Asian J Org Chem

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“…Gharpure and co-workers, while working upon alkyne-Prins type cyclization, observed that when the substrate has tethered alcohol in it 56, instead of designed indoline 57, dihydroquinoline 58 was observed as the sole product (Scheme 34). [46] The observance of later could be explained through tandem hydroalkoxylation followed by subsequent Prins type cyclization onto iminium ion, generated from vinylogous carbamate in acidic medium. Various cyclic ether fused dihydroquinolines were obtained in good yield using this cascade.…”

Section: Acid Promoted/catalyzed Intramolecular Hydroalkoxylation Cascadesmentioning

confidence: 99%

Metal‐Free Intramolecular Hydroalkoxylation of Alkyne: Recent Advances

Nanda

2021

ChemistrySelect

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Dedicated to Professor Sundarbabu BaskaranHydroalkoxylation of alkyne offers a unique platform to rapidly access structurally complex and densely functionalized oxygenbearing heterocycles. Further, to enhance the synthetic utility, various cascade reactions including hydroalkoxylation have been reported in both stereo-as well as enantioselective manner under metal and metal-free conditions. A collection of the most representative and recent methods employing metalfree hydroalkoxylation events are presented in this review article. Organocatalytic Intramolecular Hydroalkoxylation CascadeUndoubtedly, organocatalytic Michael addition reaction has come fore as one of the powerful methods for the formation of CÀ C, CÀ N, and CÀ O bonds. [12] In this context, nitroenynes have

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“…Later, in 2015, Gharpure and co-workers reported the stereoselective synthesis of indolines via alkyne iminium ion cyclization of enesulfonamides. 43 Tertiary enamides 139 derived from o-alkynyl anilines underwent intramolecular cyclization mediated by TMSOTf to afford indolines 140 in moderate to good yields and with good stereocontrol (Scheme 26). The authors presume that the process starts with the generation of an iminium ion 141, which is then intramolecularly trapped by the alkyne moiety, affording a cationic intermediate 142.…”

Section: Scheme 25 Stereoselective Synthesis Of Piperidinesmentioning

confidence: 99%

Tertiary Enamides as Versatile and Valuable Substrates to Reach Chemical Diversity

Beltran

Miesch

2020

Synthesis

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Tertiary enamides display versatile reactivity and great stability compared to their enamine congeners. This review covers progress made in the development of new methods involving the enaminic reactivity of tertiary enamides with respect to the synthesis of complex nitrogen-containing compounds. A focus on the preparation of biologically active molecules is also presented. The syntheses reported herein are classified based on their reaction type. In addition, mechanistic insights are given for most of the new transformations.1 Introduction2 [2+2] Cycloadditions3 [4+2] Cycloadditions4 Electrocyclizations and Cycloisomerizations5 Sigmatropic Rearrangements6 Nucleophilic Additions7 Tertiary Enamides as Electrophiles8 Cross-Coupling Reactions9 Tertiary-Enamide-Assisted Reactions10 Conclusion and Perspectives

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Stereoselective synthesis of 2,3-disubstituted indoline, pyrrolidine and cyclic ether-fused 1,2-dihydroquinoline derivatives using alkyne iminium ion cyclization of vinylogous carbamates: switch of regioselectivity using an internal hydroxy group as a nucleophile

Cited by 34 publications

References 43 publications

Recent Developments in the Cyclization of Alkynes and Nitrogen Compounds for the Synthesis of Indole Derivatives

Recent Developments in the Cyclization of Alkynes and Nitrogen Compounds for the Synthesis of Indole Derivatives

Metal‐Free Intramolecular Hydroalkoxylation of Alkyne: Recent Advances

Tertiary Enamides as Versatile and Valuable Substrates to Reach Chemical Diversity

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