Synthesis of Substituted Tetrahydropyrans and Tetrahydrofurans via Intramolecular Hydroalkoxylation of Alkenols

Sultana, Sabera; Devi, Ngangbam Renubala; Saikia, Anil K.

doi:10.1002/ajoc.201500314

Cited by 11 publications

(2 citation statements)

References 88 publications

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“…2,4–Dimethyl–2,4–diphenyltetrahydrofuran ( 3ba ) [ 29 ]: yellow solid; purification by flash chromatography (hexane/EtOAc), 62% yield; ( cis/trans ) = 50:50; the cis isomer is highlighted in bold; 1 H NMR (300 MHz, CDCl 3 ): δ H = 7.54–7.49 (m, 2H), 7.45–7.39 (m, 2H), 7.39–7.30 (m, 8H), 7.26–7.21 (m, 4H), 7.20–7.10 (m, 4H), 4.30 (d, J = 8.6 Hz, 1H), 4.10 (dd, J = 8.4, 1.0 Hz, 1H), 4.06 (d, J = 8.5 Hz, 1H), 3.96 (dd, J = 8.4, 0.6 Hz, 1H), 2.72 (d, J = 12.6 Hz, 1H), 2.58 (s, 2H), 2.47 (dd, J = 12.6, 1.1 Hz, 1H), 1.70 (s, 3H), 1.59 (s, 6H), 1.50 (s, 3H) ppm; MS (EI): m / z 252(M + , 0.08%), 237 (100), 207 (12), 129 (13), 117 (29), 105 (97), 91 (14), 77 (15).…”

Section: Methodsmentioning

confidence: 99%

HFIP-Promoted Synthesis of Substituted Tetrahydrofurans by Reaction of Epoxides with Electron-Rich Alkenes

Llopis

Baeza

2020

Molecules

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In the present work, the employment of fluorinated alcohols, specifically 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), as solvent and promoter of the catalyst-free synthesis of substituted tetrahydrofuranes through the addition of electron-rich alkenes to epoxydes is described. The unique properties of this fluorinated alcohol, which is very different from their non-fluorinated analogs, allows carrying out this new straightforward protocol under smooth reaction conditions affording the corresponding adducts in moderate yields in the majority of cases. Remarkably, this methodology has allowed the synthesis of new tetrahydrofuran-based spiro compounds as well as tetrahydrofurobenzofuran derivatives. The scope and limitations of the process are also discussed. Mechanistic studies were also performed pointing towards a purely ionic or a SN2-type process depending on the nucleophilicity of the alkene employed.

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Section: Methodsmentioning

confidence: 99%

HFIP-Promoted Synthesis of Substituted Tetrahydrofurans by Reaction of Epoxides with Electron-Rich Alkenes

Llopis

Baeza

2020

Molecules

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“…On the other hand, when 5a was treated with BF 3 OEt 2 , the indanone-fused tetrahydropyran 7a (CCDC 1848426 assigned for 7a′ ) was isolated in 83% yield in an unexpected manner (Scheme ). This method was realized to be general and provided efficient access to other significant analogues 7b – 7f . It is worth noting that indeno[1,2- b ]pyrans are important structural motifs prevalent in several medicinally relevant compounds …”

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confidence: 99%

Metal- and Hydride-Free Pentannulative Reductive Aldol Reaction

2018

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Traditionally, the reductive aldol reaction is a metal-catalyzed and hydride-promoted coupling between enones and aldehydes. We present a phosphine-mediated diastereoselective intramolecular reductive aldol reaction of αsubstituted dienones and aldehydes, which is metal-free and hydride-free. The synthetic utility of the reductive aldol adducts is demonstrated by elaborating them in one step to indeno[1,2-b]furanones, indeno[1,2-b]pyrans, and dibenzo-[a,h]azulen-8-ones.

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Palladium/Acid Relay Catalyzed Tandem Heck Coupling/6‐Endo Cyclization between ortho‐Halogenated Benzoates and Unactivated Terminal Alkenes for the Synthesis of 1‐Isochromanones

Wen

Zhao

et al. 2019

Adv Synth Catal

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We report a unique and expeditious route to synthesize 1-isochromanone derivatives through palladium catalyzed tandem Heck coupling/6-endo hydroacyloxylation cyclization between readily available ortho-halogenated benzoates and unactivated alkenes. Various 2-bromo or 2-iodo benzoates can be coupled efficiently with a broad range of alkenes to afford functionalized 1isochromanones in high yields. Significantly, this cost-efficient and easy-to-handle synthetic methodology will have great prospect application in the synthetic and medicinal chemistry.

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Synthesis of Substituted Tetrahydropyrans and Tetrahydrofurans via Intramolecular Hydroalkoxylation of Alkenols

Abstract: Intramolecular hydroalkoxylation of alkenols mediated by boront rifluoride etherate leads to substituted fivemembered tetrahydrofurans and six-memberedt etrahydropyrans in good yields.

Cited by 11 publications

References 88 publications

HFIP-Promoted Synthesis of Substituted Tetrahydrofurans by Reaction of Epoxides with Electron-Rich Alkenes

HFIP-Promoted Synthesis of Substituted Tetrahydrofurans by Reaction of Epoxides with Electron-Rich Alkenes

Metal- and Hydride-Free Pentannulative Reductive Aldol Reaction

Palladium/Acid Relay Catalyzed Tandem Heck Coupling/6‐Endo Cyclization between ortho‐Halogenated Benzoates and Unactivated Terminal Alkenes for the Synthesis of 1‐Isochromanones

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