Exploring the scope of Bergman Cyclization mediated cascade reaction of alkenyl enediynes: synthesis of [5]helicene and amino acid appended [4]helicenes

Roy, Snigdha; Basak, Amit

doi:10.1016/j.tet.2012.12.064

Cited by 12 publications

(13 citation statements)

References 41 publications

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“…In the first step, the benzaldehyde derivatives were converted into their corresponding α,β-unsaturated ester S2 employing a halo-Wittig reaction, and the product reduced to the corresponding α,β-unsaturated alcohol S3 using diisobutylaliminium hydride (DIBAL-H). 19 Finally, compound S3 underwent "Sonogashira coupling" with acetylenic compound S1 synthesized previously leading to the formation of the desired starting material 7a. General Synthesis of α,β-Unsaturated Esters S2 via Halo-Wittig Reaction (See Scheme S1b in the Supporting Information).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…9, 141.7, 139.1, 137.9, 133.0, 132.7, 129.7, 129.1, 125.9, 125.8, 122.9, 120.0, 118.8, 117.0, 115.4, 9, 143.6, 141.7, 139.2, 133.0, 129.2 (app q, J C−F = 32.7 Hz), 128.7, 125.8 (q, J C−F = 3.6 Hz), 124.1 (app q, J C−F = 270. 5 Hz),122.9,119.9,118.3,116.9,115.3,104.1 30.7;19 5, 152.9, 141.6, 141.5, 133.0, 131.4, 129.3, 125.9, 125.8, 125.7, 122.7, 120.0, 119.6, 114.3, 55.3, 29.8 8, 152.6, 151.0, 141.5, 139.8, 132.9, 129.1, 125.7, 125.5, 122.5, 119.9, 118.8, 116.8, 115.9, 115.5, 117.7, 113.3, 103.3, 55.9, 55.6, 24.3 3-(Thiophen-2-ylmethyl)naphtho [1,2-b]furan-4-amine (1ah). Brown gum (23.0 mg, 25%), R f = 0.41 (10% ethyl acetate in petroleum ether); 1 H NMR (CDCl 3 , 600 MHz) δ H 8.16 (d, J = 7.8 Hz, 1H), 7.65− 7.63 (m, 2H), 7.38 (t, J = 7.8 Hz, 1H), 7.34 (t, J = 7.5 Hz, 1H), 7.22 (d, J = 4.8 Hz, 1H), 6.97−6.95 (m, 1H), 6.90−6.89 (m, 1H), 6.70 (s, 1H), 4.41 (s, 2H), 3.89 (brs, 2H); 13 C{ 1 H} NMR (CDCl 3 , 150 MHz) δ C 152.8, 143.3, 141.2, 139.5, 133.0, 127.2, 125.8, 125.7, 125.2, 124.8, 122.7 119.9, 119.1, 116.9, 115.3, 103.8, 25.5; HRMS (ESI) m/z calcd for C 17 H 14 NOS [M + H] + 280.0796, found 280.0789.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…2, 143.5, 141.5, 131.5, 128.8, 128.7, 128.3, 126.4, 125.5 (q, J C−F = 3.8 Hz), 125.3, 124.2 (app q, J C−F = 270. 1 Hz),123.2,123.1,121.5,119.9,119.7,118.1,29.9;19 3-(4-Methylbenzyl)naphtho [1,2-b]furan (1be). Brown solid (37.2 mg, 76%), R f = 0.73 (5% ethyl acetate in petroleum ether, v/v); mp 44− 46 °C 1 H NMR (CDCl 3 , 600 MHz) δ H 8.31 (d, J = 7.8 Hz, 1H), 7.92 (d, J = 8.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…1H),3H),1H),7.36 (td,J = 8.7,2.4 Hz,1H),4H),1H),4.12 (s, 2H); 13 C{ 1 H} NMR (CDCl 3 , 150 MHz) δ C 160. 2 (d,J = 243.0 Hz),151.2,141.3,139.3,132.3 (d,J = 9.0 Hz),128.6,128.5,126.4,122.9,122.4 (d,J = 9.0 Hz),122.3 (d,J = 4.5 Hz),120.8,119.8,118.5,116.3,116.1,111.8,111.7,30.1;19 Procedure for the Synthesis of 7-Benzyl-2,4-dimethoxyfuro[3,2h]quinazoline (1bh). A mixture of Pd(OAc) 2 bpy (2.7 mg, 0.007 mmol, 5 mol %) and D-CSA (82.4 mg, 0.355 mmol, 1.5 equiv) in dry THF (2 mL) was stirred at 60 °C under argon atmosphere.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…The requisite starting material 8b was synthesized as depicted in Scheme S4. The starting compound S4 19 was synthesized by executing the Wittig reaction on 2-iodobenzaldehyde derivative, which underwent coupling with S10 (see Scheme S3 in the Supporting Information) under Sonogashira reaction conditions resulting in the formation of S11. Finally, exposure of S11 under acidic conditions led to 8b.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Palladium(II)-Catalyzed Cascade Reactions of Ene–Ynes Tethered to Cyano/Aldehyde: Access to Naphtho[1,2-b]furans and Benzo[g]indoles

Jash

Pramanik

et al. 2019

J. Org. Chem.

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An efficient palladium(II)-catalyzed cascade reaction of ene−yne substrates carrying cyano/aldehyde group is described. It involves successive hetero-and benz-annulations in one pot via transoxo/aminopalladation onto alkyne, followed by 1,2-addition to cyano/ aldehyde, providing a convenient synthesis of both naphtho[1,2b]furans and benzo[g]indoles. The reaction constitutes a fast intramolecular assembly through several carbon−carbon and carbon− heteroatom bond formations taking place in one pot. The reactions are operationally simple, compatible with a range of functional groups and atom-economical in nature. Article pubs.acs.org/joc

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

See 3 more Smart Citations

Palladium(II)-Catalyzed Cascade Reactions of Ene–Ynes Tethered to Cyano/Aldehyde: Access to Naphtho[1,2-b]furans and Benzo[g]indoles

Jash

Pramanik

et al. 2019

J. Org. Chem.

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A Half Century of the Sonogashira Reaction

Frankenberger,

Wendinger,

Scherer

et al. 2025

Organic Reactions

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Conjugated alkynes are valuable intermediates in the synthesis of natural products, agrochemicals, pharmaceuticals, fine chemicals, and organic molecular materials. Since its introduction in 1975, the palladium‐catalyzed Sonogashira reaction has become the primary choice for the construction of sp–sp 2 carbon–carbon bonds in aryl‐, heteroaryl‐, and alkenyl‐substituted alkynes. A vast range of reaction conditions have been explored to expand and optimize the scope of the Sonogashira reaction, including sustainable variants, microwave‐assisted cross couplings, and cross couplings performed in water. Research efforts also target the development of improved catalytic systems for the Sonogashira reaction, such as solid‐supported palladium catalysts and nanoparticles, the use of N ‐heterocyclic carbenes (NHCs) as ligands, as well as copper‐free variants of the reaction. This Chapter reviews the application of the palladium‐catalyzed Sonogashira cross coupling of terminal alkynes with aryl or alkenyl halides and triflates. Coupling reactions that form conjugated alkynes via alternative methods, or use different electrophiles, catalysts, or alkynes, are also briefly described.

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Alkyne‐Based Syntheses of Carbo‐ and Heterohelicenes

Gulevskaya

Tonkoglazova

2022

Adv Synth Catal

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[n]Helicenes are polycyclic aromatic molecules in which n ortho‐condensed benzene or other aromatic rings give rise to helical chiral and highly conjugated structures. The unique screw shape, helically extended π‐system and intriguing electronic and chirooptical properties of these molecules have attracted scientific interest for decades. The applications of helicenes have now expanded into several fields including material science, nanoscience, biochemistry, supramolecular and polymer chemistry. Despite the great theoretical and practical interest in helicenes, their synthesis remains a challenge. Among synthetic approaches to helicenes, alkyne cyclizations have great potential, since carbon‐rich high‐energy alkynes can form aromatic rings via cycloisomerizations. These processes are atom‐economic. In addition, alkyne reactions are highly favorable thermodynamically. This review focuses on alkyne‐based syntheses of carbo‐ and heterohelicenes (2000–2022). These syntheses are obviously multistage. In the review, they are systematized in terms of the key step leading to the formation of a helical shape. The methods are grouped into two categories: (a) metal‐free syntheses and (b) transition‐metal‐catalyzed syntheses. This division is very arbitrary, since catalytic Sonogashira and Suzuki‐Miyaura reactions and others are often used to prepare starting materials in the syntheses of the first group. Most of the publications on the topic are related to transition‐metal‐catalyzed syntheses of helicenes.

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Exploring the scope of Bergman Cyclization mediated cascade reaction of alkenyl enediynes: synthesis of [5]helicene and amino acid appended [4]helicenes

Cited by 12 publications

References 41 publications

Palladium(II)-Catalyzed Cascade Reactions of Ene–Ynes Tethered to Cyano/Aldehyde: Access to Naphtho[1,2-b]furans and Benzo[g]indoles

Palladium(II)-Catalyzed Cascade Reactions of Ene–Ynes Tethered to Cyano/Aldehyde: Access to Naphtho[1,2-b]furans and Benzo[g]indoles

A Half Century of the Sonogashira Reaction

Alkyne‐Based Syntheses of Carbo‐ and Heterohelicenes

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