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. 2017 Oct 25;4(10):170748.
doi: 10.1098/rsos.170748. eCollection 2017 Oct.

Fe(OTf)3-catalysed Friedel-Crafts reaction of benzenoid arenes with α,β-unsaturated carbonyl compounds: easy access to 1,1-diarylalkanes

Aditya Bhattacharya  1 , Pushpendra Mani Shukla  1 , Biswajit Maji  1
Affiliations

Fe(OTf)3-catalysed Friedel-Crafts reaction of benzenoid arenes with α,β-unsaturated carbonyl compounds: easy access to 1,1-diarylalkanes

Aditya Bhattacharya et al. R Soc Open Sci. .

Abstract

A simple and efficient method for the synthesis of 1,1-diarylalkanes via the Friedel-Crafts-type alkylation reaction of electron-rich arenes with cinnamic acid ester derivatives or chalcones is reported. Iron triflate has been found to be the best catalyst for the Friedel-Crafts-type alkylation reaction with α,β-unsaturated carbonyl compounds. This reaction afforded β,β-diaryl carbonyl compounds in good yields (65-93%) and with excellent regioselectivities. Remarkably, this method is also compatible with a variety of indoles to provide 3-indolyl-aryl carbonyl compounds in excellent yields. Great efforts have been made to deduce a plausible reaction mechanism based on isotopic labelling experiments.

Keywords: 1,1-diarylalkane; Friedel–Crafts alkylation; iron triflate; β,β-diaryl carbonyl compounds.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1.
Figure 1.
Representative examples of 1,1-diarylalkanes with biological activities.
Scheme 1.
Scheme 1.
1,1-Diarylalkane synthesis.
Figure 2.
Figure 2.
Regioisomers of arene.
Scheme 2.
Scheme 2.
Reaction condition of Friedel–Crafts alkylation reaction of indoles with chalcones: chalcone (1.0 equiv), indole 4 (1.2 equiv) and catalyst Fe(OTf)3 (10 mol%) are heated to 85°C in DCE for 12 h. Isolated yield after column chromatography.
Scheme 3.
Scheme 3.
Control experiments to give insight on the reaction mechanism.
Scheme 4.
Scheme 4.
A plausible reaction mechanism.
See this image and copyright information in PMC

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