Synthesis and Reactivity of an Aluminium N‐heterocyclic Aminal.

Tethered N‐heterocyclic carbenes (NHCs) are an emerging class of ligand, as they feature all the desirable aspects of NHCs (ease of synthesis, high tunabilty) but also enable metal‐ligand cooperativity when combined with Lewis acidic metal centres due to the donor‐acceptor nature of the complexes formed. Herein we report a simple ethoxy‐tethered NHC for the stabilisation of Al(III) hydrides, resulting in the unexpected formation of a bicyclic N‐heterocyclic aminal (1). Compound 1 behaves as a metal hydride, capable of reducing benzophenone and carbodiimide to yield compounds 2 and 3, respectively. Furthermore, we show that 1 behaves as an efficient catalyst in the dehydrocoupling of amine‐boranes due to the hemi‐labile nature of the supporting ligand. [ABSTRACT FROM AUTHOR]