Fe(OTf)3‐Catalyzed α‐Benzylation of Aryl Methyl Ketones with Electrophilic Secondary and Aryl Alcohols |
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Authors: | Xiaojuan Pan Minghao Li Prof Dr Yanlong Gu |
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Institution: | 1. Hubei Key Laboratory of Material Chemistry and Service Failure, Key Laboratory for Large‐Format Battery Materials and System, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), 1037 Luoyu road, Hongshan District, Wuhan 430074 (China), Fax: (+86)?027‐87‐54‐37‐45;2. State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (P.R. China) |
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Abstract: | Acid‐catalyzed Friedel–Crafts alkylation of 1,3‐dicarbonyl compounds with electrophilic alcohols, is known to be an effective C? C bond forming reaction. However, until now, this reaction has not been amenable for α‐alkylation of aryl methyl ketones because of the notoriously low nucleophilicities of these compounds. Therefore, α‐alkylation of aryl methyl ketone relies on precious metal catalysts and also, the use of primary alcohols is mandatory. In this study, we found that a system composed of a Fe(OTf)3 catalyst and chlorobenzene solvent is sufficient to promote the title Friedel–Crafts reaction by using benzhydrols as electrophiles. 3,4‐Dihydro‐9‐(2‐hydroxy‐4,4‐dimethyl‐6‐oxo‐1‐cyclohexen‐1‐yl)‐3,3‐dimethyl‐xanthen‐1(2 H)‐one was also applicable as an electrophile in this type of benzylation reaction. On the basis of this result, a three‐component reaction of salicylaldehyde, dimedone, and aryl methyl ketone was also developed, and this provided an efficient way for the synthesis of densely substituted 4H‐chromene derivatives. |
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Keywords: | alkylation aryl methyl ketone Friedel– Crafts reaction iron catalysis three‐component reaction |
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