Synthesis of long-chain alkanoyl benzenes by an aluminum(III) chloride-catalyzed destannylative acylation reaction

Max Roemer*, Sinead T. Keaveney, Nicholas Proschogo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

This paper describes the facile synthesis of haloaryl compounds with long-chain alkanoyl substituents by the destannylative acylation of haloaryls bearing tri-n-butyltin (Bu3Sn) substituents. The method allows the synthesis of many important synthons for novel functional materials in a highly efficient manner. The halo-tri-n-butyltin benzenes are obtained by the lithium–halogen exchange of commercially available bis-haloarenes and the subsequent reaction with Bu3SnCl. Under typical Friedel–Crafts conditions, i.e., the presence of an acid chloride and AlCl3, the haloaryls are acylated through destannylation. The reactions proceed fast (<5 min) at low temperatures and thus are compatible with aromatic halogen substituents. Furthermore, the method is applicable to para-, meta-, and ortho-substitution and larger systems, as demonstrated for biphenyls. The generated tin byproducts were efficiently removed by trapping with silica/KF filtration, and most long-chain haloaryls were obtained chromatography-free. Molecular structures of several products were determined by X-ray single-crystal diffraction, and the crystal packing was investigated by mapping Hirshfeld surfaces onto individual molecules. A feasible reaction mechanism for the destannylative acylation reaction is proposed and supported through density functional theory (DFT) calculations. DFT results in combination with NMR-scale control experiments unambiguously demonstrate the importance of the tin substituent as a leaving group, which enables the acylation.
Original languageEnglish
Pages (from-to)9007-9022
Number of pages16
JournalJournal of Organic Chemistry
Volume86
Issue number13
DOIs
Publication statusPublished - 2 Jul 2021

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