Reversible [4 + 1] Cycloaddition of Arenes by a “Naked” Acyclic Aluminyl Compound
Debotra Sarkar, Petra Vasko, Aisling Roper, Agamemnon E. Crumpton, Matthew M. D. Roy, Liam P. Griffin, Charlotte Bogle, Simon Aldridge
Abstract
High Resolution Image Download MS PowerPoint Slide 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.