An organocatalytic method for the synthesis of some novel xanthene derivatives by the intramolecular Friedel–Crafts reaction

Yıldız, Tülay; Küçük, Hatice Başpınar

doi:10.1039/c6ra27094h

Cited by 25 publications

(10 citation statements)

References 42 publications

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“…[48] Screening different Brønsted acids revealed the N-triflylphosphoramide to be the most efficient organocatalyst for this transformation. [48] Screening different Brønsted acids revealed the N-triflylphosphoramide to be the most efficient organocatalyst for this transformation.…”

Section: Sequential C-o Bond Formation Followed By C-c Bond Formationmentioning

confidence: 99%

“…Further the use of small organic molecules (organocatalysts) for the same protocol allowed the synthesis of the title 9-arylxanthene compounds to be carried out in a metal free environmentally benign fashion (Scheme 20). [48] Screening different Brønsted acids revealed the N-triflylphosphoramide to be the most efficient organocatalyst for this transformation. In presence of the Brønsted acid catalyst the starting benzhydrols dehydrate to form the carbocationic species which takes part in the intramolecular Friedel-Crafts alkylation to give the target product.…”

Section: Sequential C-o Bond Formation Followed By C-c Bond Formationmentioning

confidence: 99%

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Conformationally Restricted Triarylmethanes: Synthesis, Photophysical Studies, and Applications

2018

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Triarylmethanes, compounds in which the central carbon atom is attached to three aryl rings, have a wide variety of photophysical properties which are utilized in the dye industry and also in the development of novel fluorescent tags and biomarkers. The aryl rings attached to the central carbon atom of the parent molecule triphenylmethane can freely rotate. Bridging the aryl rings of triarylmethanes with heteroatoms or through bonds decreases the conformational flexibility enjoyed by the parent molecules. Conformationally restricted triarylmethane (CRT) molecules like 9‐arylxanthenes (oxygen bridging), 9‐arythioxanthenes (sulfur bridging), 9,10‐dihydro,9‐arylacridines (nitrogen bridging), and 9‐arylfluorenes (bridging through C–C bond) have decreased conformational flexibility and display amphihydric behavior which results in benzenoid structure and quinoid structure of these molecules. The quinoid form of these molecules displays very rich photophysical properties which are the subject of this review. These molecules also have widespread utility, and over the last decade, a number of studies have been focused on the synthesis, photophysical properties, and applications of molecules derived from this core structure. Through this review, we intend to give the readers an outlook on the different strategies employed to synthesize these molecules and also provide a broader perspective on the various intriguing properties of these molecules. The applications of these classes of molecules in diverse fields like photocatalysis, chemical biology, pharmaceutical chemistry, and bio‐imaging are discussed. Also, the areas that need to be further developed are highlighted, which may provide a further impetus in the development of this class of molecules.

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Section: Sequential C-o Bond Formation Followed By C-c Bond Formationmentioning

confidence: 99%

Section: Sequential C-o Bond Formation Followed By C-c Bond Formationmentioning

confidence: 99%

Conformationally Restricted Triarylmethanes: Synthesis, Photophysical Studies, and Applications

2018

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“…After these developments, the intramolecular FCA method using π-activated alcohols has frequently been used for xanthene synthesis. Some of these methods are the stereoselective synthesis of 9-vinyl-substituted unsymmetrical xanthenes and thioxanthenes by intramolecular FCA reaction [ 39 ], Lewis acid-catalyzed intramolecular FCA [ 40 ], and the synthesis of xanthenes and thioxanthenes by intramolecular FCA catalyzed with organic Brønsted superacid, which are our works [ 41 – 42 ]. According to the literature, there are also hydroarylation methods with FCA, which are made by unactivated alkenes instead of π-activated alcohols.…”

Section: Introductionmentioning

confidence: 99%

“…As a continuation of our series of works to develop organic Brønsted acid-catalyzed cyclization reactions [ 41 – 42 ], herein we report a highly efficient intramolecular FCA of appropriate unactivated alkenes with a polyaromatic structure in order to synthesize xanthene derivatives. We developed a new intramolecular FCA method by activating alkenes working under mild reaction conditions and have widened the substrate scope of alkenes to those containing varied electronic and steric properties.…”

Section: Introductionmentioning

confidence: 99%

Transition-metal-free intramolecular Friedel–Crafts reaction by alkene activation: A method for the synthesis of some novel xanthene derivatives

Yıldız¹,

Baştaş²,

Küçük³

2021

Beilstein J. Org. Chem.

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In this work, new derivatives (substituted 9-methyl-9-arylxanthenes) of xanthene compounds (5a–l) of possible biological significance were synthesized by developing a new synthesis method. In order to obtain xanthene derivatives, the original alkene compounds to be used as the starting materials were synthesized in four steps using appropriate reactions. A cyclization reaction by intramolecular Friedel–Crafts alkylation was carried out in order to synthesize the desired xanthene derivatives using the alkenes as starting compounds. The intramolecular Friedel–Crafts reaction was catalyzed by trifluoroacetic acid (TFA) and provided some novel substituted 9-methyl-9-arylxanthenes with good yields at room temperature within 6–24 hours. As a result, an alkene compound was used for activation with TFA in the synthesis of xanthene through intramolecular Friedel–Crafts alkylation for the first time.

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“…To our knowledge, employing benzhydrol or 2-phenoxybenzaldehyde derivatives as starting materials is one of the classic methods for xanthene synthesis. 9 In 2020, Ramanathan and co-workers reported the synthesis of 9-aryl xanthenes/thioxanthenes with triphenylmethanol derivatives as substrates and NaHSO 4 /SiO 2 as a catalyst. 10 However, these substrates in this work are not commercially available and suffer from multiple-step synthesis.…”

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confidence: 99%

Electrochemical benzylic C–H arylation of xanthenes and thioxanthenes without a catalyst and oxidant

et al. 2022

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An organocatalytic method for the synthesis of some novel xanthene derivatives by the intramolecular Friedel–Crafts reaction

Abstract: An efficient organocatalytic method for the synthesis of new substituted 9-arylxanthenes (2a–2u) starting from diarylcarbinol compounds with an arenoxy group (1a–1u) has been developed using the intramolecular Friedel–Crafts reaction.

Cited by 25 publications

References 42 publications

Conformationally Restricted Triarylmethanes: Synthesis, Photophysical Studies, and Applications

Conformationally Restricted Triarylmethanes: Synthesis, Photophysical Studies, and Applications

Transition-metal-free intramolecular Friedel–Crafts reaction by alkene activation: A method for the synthesis of some novel xanthene derivatives

Electrochemical benzylic C–H arylation of xanthenes and thioxanthenes without a catalyst and oxidant

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