Facile Benzylic Alkylation of Arenes with Alcohols by Catalysis with Spirocyclic NHC IrIII Pincer Complex

Kun-Long Dai; Qi-Long Chen; Wen-Ping Xie; Ka Lu; Zhi-Bo Yan; Meng Peng; Chang-Kun Li; Yong-Qiang Tu; Tong-Mei Ding

doi:10.1002/anie.202206446

Facile Benzylic Alkylation of Arenes with Alcohols by Catalysis with Spirocyclic NHC Ir^III Pincer Complex

Angew Chem Int Ed Engl. 2022 Sep 19;61(38):e202206446. doi: 10.1002/anie.202206446. Epub 2022 Aug 11.

Authors

Kun-Long Dai¹, Qi-Long Chen², Wen-Ping Xie¹, Ka Lu², Zhi-Bo Yan², Meng Peng², Chang-Kun Li¹, Yong-Qiang Tu^{1

2}, Tong-Mei Ding¹

Affiliations

¹ School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China.
² State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China.

PMID: 35866449
DOI: 10.1002/anie.202206446

Abstract

A facile benzylic alkylation of indenes and other arenes was developed from readily available primary and secondary alcohols using our newly investigated CCC pincer Ir^III catalyst (SNIr-H). Excellent regioselectivity and yield (89 %) of the C3-alkylated indenes were obtained. Additionally, the challenging sp² C-alkylation was readily accomplished. This method could be utilized for the synthesis of the analogs of a histamine H1 receptor antagonist and the functional material template molecule, indeno[2,1-a]indene. A hemilabile Ir^III -dihydride intermediate was proposed based on control experiments and previous density functional theory (DFT) calculations for the borrowing hydrogen mechanism and is key to the success of this Ir^III catalyst in the reduction of unactivated multi-substituted olefin intermediates.

Keywords: Alkylation; Borrowing Hydrogen; Hemilabile Intermediate; Iridium Catalysis; Synthetic Methods.

Abstract

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