Synthesis of Bisflavanol-Type Natural Products and Their Analogues­ via Self-Coupling of C8-Methylol Catechin Derivatives

A highly efficient and regioselective self-coupling of C8-methylol catechin derivatives is developed for the synthesis of dimeric flavanol analogues under metal-free and mild conditions. Its applicability is showcased by the efficient synthesis of bisflavanol-type natural products bis-8,8′-catechinylmethane, bis-8,8′-epicatechinylmethane, talienbisflavan A, and oolonghomobisflavan A. The novel self-coupling mechanism sheds new light on the classical Friedel–Crafts alkylation mechanism in acid-catalyzed catechin–formaldehyde condensation.

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Triflic acid-catalyzed metal-free synthesis of (E)-2-cyanoacrylamides and 3-substituted azetidine-2,4-diones

New Journal of Chemistry ◽

10.1039/c7nj05169g ◽

2018 ◽

Vol 42 (8) ◽

pp. 6433-6440 ◽

Cited By ~ 5

Author(s):

Bapurao D. Rupanwar ◽

Santosh S. Chavan ◽

Anil M. Shelke ◽

Gurunath M. Suryavanshi

Keyword(s):

Biologically Active ◽

Efficient Synthesis ◽

Triflic Acid ◽

Metal Free ◽

Highly Efficient ◽

Acid Catalyzed

A TfOH-catalyzed highly efficient synthesis of biologically active (E)-2-cyanoacrylamides and 3-substituted azetidine-2,4-diones has been reported with 64–94% yields under metal-free conditions.

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Oxidation of 2-methylpyrroles with perchlorinated iron(III) metalloporphyrin catalysts: a versatile synthesis of symmetric and asymmetric dipyrromethanes

Canadian Journal of Chemistry ◽

10.1139/v98-190 ◽

1998 ◽

Vol 76 (10) ◽

pp. 1467-1473 ◽

Cited By ~ 2

Author(s):

Veranja Karunaratne ◽

David Dolphin

Keyword(s):

Catalytic Oxidation ◽

Allylic Alcohols ◽

The Novel ◽

Efficient Synthesis ◽

Mild Conditions ◽

Metalloporphyrin Catalysts

A variety of substituted 2-methylpyrroles (3-8) were oxidized using the metalloporphyrin catalysts iron(III) meso-tetra(2,6-dichloro-3-sulphonatophenyl)-β-octachloroporphyrin chloride 1 and iron(III) meso-tetra(2,6-dichlorophenyl)-β-octachloroporphyrin chloride 2 under very mild conditions. Treatment of the resulting allylic alcohols 3a-8a with α-free pyrroles 9 and 10 resulted in a very efficient synthesis of the corresponding dipyrromethanes 3b-8b and 3c-8c. Furthermore, the above allylic alcohols when treated with furfurylamine produced the novel (2-furylmethyl)-2-pyrrolylmethylamines 3d-8d.Key words: catalytic oxidation, metalloporphyrins, pyrroles, dipyrromethanes, polyhalogenated porphyrins.

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Introduction of N,N'-disulfonylhydrazines as new sulfonylating reagents for highly efficient synthesis of (E)-β-iodovinyl arenesulfones under mild conditions

Chinese Chemical Letters ◽

10.1016/j.cclet.2019.12.040 ◽

2020 ◽

Vol 31 (7) ◽

pp. 1877-1880

Author(s):

Dongping Luo ◽

Lin Min ◽

Weiping Zheng ◽

Lidong Shan ◽

Xinyan Wang ◽

...

Keyword(s):

Efficient Synthesis ◽

Mild Conditions ◽

Highly Efficient

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Metal-Free Mesoporous SiO2 Nanorods as a Highly Efficient Catalyst for the Baeyer–Villiger Oxidation under Mild Conditions

ACS Sustainable Chemistry & Engineering ◽

10.1021/acssuschemeng.7b04167 ◽

2018 ◽

Vol 6 (5) ◽

pp. 5868-5876 ◽

Cited By ~ 9

Author(s):

Xueyao Zhang ◽

Honglei Yang ◽

Guangxue Yang ◽

Shuwen Li ◽

Xiang Wang ◽

...

Keyword(s):

Efficient Catalyst ◽

Metal Free ◽

Mild Conditions ◽

Highly Efficient ◽

Mesoporous Sio2 ◽

Villiger Oxidation

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A mild, general, and metal-free method for site-specific deuteration induced by visible light using D2O as the source of deuterium atoms

Green Chemistry ◽

10.1039/c9gc04096j ◽

2020 ◽

Vol 22 (3) ◽

pp. 669-672 ◽

Cited By ~ 4

Author(s):

Shuai Shi ◽

Ruining Li ◽

Liangming Rao ◽

Zhankui Sun

Keyword(s):

Visible Light ◽

Functional Group ◽

Site Specific ◽

Metal Free ◽

Mild Conditions ◽

Highly Efficient ◽

Radical Approach

Visible light induced desulfurization–deuteration method was developed using D2O as the source of deuterium atoms. This radical approach features mild conditions, broad substrate scope, highly efficient D-incorporation and excellent functional group compatibility.

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Highly Efficient Synthesis of Hindered 3-Azoindoles via Metal-Free C–H Functionalization of Indoles

Synthesis ◽

10.1055/s-0039-1690048 ◽

2020 ◽

Vol 52 (04) ◽

pp. 574-580

Author(s):

Nicolas Jacob ◽

Lucas Guillemard ◽

Joanna Wencel-Delord

Keyword(s):

Steric Hindrance ◽

Room Temperature ◽

Efficient Synthesis ◽

Atom Economy ◽

Photochromic Compounds ◽

Metal Free ◽

Highly Efficient ◽

Simple Protocol ◽

Potential Applications

Although 3-azoindoles have recently emerged as an appealing family of photoswitch molecules, the synthesis of such compounds has been poorly covered in the literature. Herein a high-yielding and operationally simple protocol is reported allowing the synthesis of 3-azoindoles, featuring important steric hindrance around the azo motif. Remarkably, this C–H coupling is characterized by excellent atom economy and occurs under metal-free conditions, at room temperature, and within few minutes, delivering the expected products in excellent yields (quantitatively in most of the cases). Accordingly, a library of new molecules, with potential applications as photochromic compounds, is prepared.

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