Reversible [4 + 1] Cycloaddition of Arenes by a "Naked" Acyclic Aluminyl Compound

Debotra Sarkar; Petra Vasko; Aisling F Roper; Agamemnon E Crumpton; Matthew M D Roy; Liam P Griffin; Charlotte Bogle; Simon Aldridge

doi:10.1021/jacs.4c00376

Reversible [4 + 1] Cycloaddition of Arenes by a "Naked" Acyclic Aluminyl Compound

J Am Chem Soc. 2024 May 1;146(17):11792-11800. doi: 10.1021/jacs.4c00376. Epub 2024 Apr 16.

Authors

Debotra Sarkar¹, Petra Vasko², Aisling F Roper¹, Agamemnon E Crumpton¹, Matthew M D Roy¹, Liam P Griffin¹, Charlotte Bogle¹, Simon Aldridge¹

Affiliations

¹ Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K.
² Department of Chemistry, University of Helsinki, A.I. Virtasen Aukio 1, P.O. Box 55, Helsinki FI-00014, Finland.

Abstract

The large steric profile of the N-heterocyclic boryloxy ligand, -OB(NDippCH)₂, and its ability to stabilize the metal-centered HOMO, are exploited in the synthesis of the first example of a "naked" acyclic aluminyl complex, [K(2.2.2-crypt)][Al{OB(NDippCH)₂}₂]. This system, which is formed by substitution at Al^I (rather than reduction of Al^III), represents the first O-ligated aluminyl compound and is shown to be capable of hitherto unprecedented reversible single-site [4 + 1] cycloaddition of benzene. This chemistry and the unusual regioselectivity of the related cycloaddition of anthracene are shown to be highly dependent on the availability (or otherwise) of the K⁺ countercation.