HFIP-promoted halo-carbocyclizations of <i>N</i>- and <i>O</i>-tethered arene–alkene substrates to access all halo (X = Br, I, Cl)-functionalized tetrahydroquinoline and chroman cores

Shukla, Pushpendra mani; Bhattacharya, Aditya; Pratap, Aniruddh; Pradhan, Akash Kumar; Sinha, Puspita; Soni, Tanishk; Maji, Biswajit

doi:10.1039/d2ob01597h

Cited by 6 publications

(1 citation statement)

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“…Although no metal was used in this protocol, stoichiometric byproduct triphenylphosphine oxide was produced, making this protocol less attractive. On the other hand, 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) has been widely applied in organic synthesis for its unique ability to stabilize ionic species. − In continuation of our interest in the synthesis of quinazolinone derivatives, we tried to find whether HFIP could promote the alkylation reaction of quinazolinones and alcohols in the absence of any metal catalysts.…”

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confidence: 99%

1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) Promoted N-Alkylation of Quinazolinones through Nucleophilic Substitution of Benzyl Alcohols

Zhang,

Liu

et al. 2023

J. Org. Chem.

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confidence: 99%

1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) Promoted N-Alkylation of Quinazolinones through Nucleophilic Substitution of Benzyl Alcohols

Zhang,

Liu

et al. 2023

J. Org. Chem.

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K₃PO₄–Mediated Synthesis of Chromeno–[3,4‐c]isoxazole from 3–Nitro–2H–chromene and α–Chloro Aldehyde via Michael Addition/C−Cl Bond Cleavage/Deformylation as Key Fragmentation Sequences

Pratap,

Shukla,

Giri

et al. 2024

Adv Synth Catal

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Here we report a transition metal– and oxidant–free annulation cascade method for the synthesis of chromeno–isoxazoles. The annulation reaction involves easily accessible starting materials, 3‐nitro‐2H‐chromene and α‐chloro aldehyde, yielding the structurally intriguing framework, chromeno[3,4‐c]isoxazoles employed by tripotassium phosphate as a base. The isoxazole ring construction over the 2H–chromene unit is believed to occur via a series of multiple reaction sequences. Here, the enolate generation/Michael addition/C–Cl bond cleavage/oxy–anionic addition to reactive tethered‐aldehyde/deformylation via retro– C–C and N–O bond cleavages are the most possible sequences which furnish the desired end–product in good chemical yields. The multiple reaction sequences occur in one‐pot at mild conditions, supported by experimental results and a few control experiments including DFT studies. This process exhibits a broad substrates scope illustrating good functional group compatibility towards both the nitrochromenes and aldehydes, and thus prove to be a general and efficient protocol for the synthesis of chromeno[3,4–c]isoxazoles. Overall, the use of nitrochromene as the limiting reagent, noteworthy functional group tolerance, scalability including great applications like chiral pool strategy towards the synthesis of enantioenriched chromeno‐isoxazole are the additional features.

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Synthesis of CF₃, CF₂H‐Substituted, Epoxide‐Fused Heterocycles with Prop‐2‐ynylsulfonium salts

Cheng

Yao

et al. 2023

Asian J Org Chem

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The synthesis CF3, CF2H‐Substituted, epoxide‐fused heterocycles was performed efficiently using [4+2]/[2+1]‐annulation of ortho‐amino trifluoracetophenone or difluoroacetophenone derivatives and prop‐2‐ynylsulfonium salts. This resulted in a wide range of target compounds with various substituents and functionalities in moderate to good yields. The transformation makes it an alternative method to previous protocols. Moreover, the successful synthesis finds application in pharmaceutical and biomedical of the investigated compounds, which are expected to develop further.

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HFIP-promoted halo-carbocyclizations of N- and O-tethered arene–alkene substrates to access all halo (X = Br, I, Cl)-functionalized tetrahydroquinoline and chroman cores

Abstract: A new method for the stereoselective metal-, additive- and oxidant-free Friedel-Crafts-type halo-carbocyclization of N- and O-tethred arene-olefin substrates is reported, involving reaction with a suitable electrophilic halogenating reagent (NXS/DCDMH) in...

Cited by 6 publications

References 102 publications

1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) Promoted N-Alkylation of Quinazolinones through Nucleophilic Substitution of Benzyl Alcohols

1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) Promoted N-Alkylation of Quinazolinones through Nucleophilic Substitution of Benzyl Alcohols

K₃PO₄–Mediated Synthesis of Chromeno–[3,4‐c]isoxazole from 3–Nitro–2H–chromene and α–Chloro Aldehyde via Michael Addition/C−Cl Bond Cleavage/Deformylation as Key Fragmentation Sequences

Synthesis of CF₃, CF₂H‐Substituted, Epoxide‐Fused Heterocycles with Prop‐2‐ynylsulfonium salts

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HFIP-promoted halo-carbocyclizations of N- and O-tethered arene–alkene substrates to access all halo (X = Br, I, Cl)-functionalized tetrahydroquinoline and chroman cores

Abstract: A new method for the stereoselective metal-, additive- and oxidant-free Friedel-Crafts-type halo-carbocyclization of N- and O-tethred arene-olefin substrates is reported, involving reaction with a suitable electrophilic halogenating reagent (NXS/DCDMH) in...

Cited by 6 publications

References 102 publications

1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) Promoted N-Alkylation of Quinazolinones through Nucleophilic Substitution of Benzyl Alcohols

1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) Promoted N-Alkylation of Quinazolinones through Nucleophilic Substitution of Benzyl Alcohols

K3PO4–Mediated Synthesis of Chromeno–[3,4‐c]isoxazole from 3–Nitro–2H–chromene and α–Chloro Aldehyde via Michael Addition/C−Cl Bond Cleavage/Deformylation as Key Fragmentation Sequences

Synthesis of CF3, CF2H‐Substituted, Epoxide‐Fused Heterocycles with Prop‐2‐ynylsulfonium salts

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K₃PO₄–Mediated Synthesis of Chromeno–[3,4‐c]isoxazole from 3–Nitro–2H–chromene and α–Chloro Aldehyde via Michael Addition/C−Cl Bond Cleavage/Deformylation as Key Fragmentation Sequences

Synthesis of CF₃, CF₂H‐Substituted, Epoxide‐Fused Heterocycles with Prop‐2‐ynylsulfonium salts