Precise Transfer of an Aluminium Atom: An Avenue to Aluminium Heterocycles

Abstract

Synthetic chemistry targets building up molecular complexity using simple substrates through simple processes. We disclose an unprecedented Al-atom transfer strategy for the synthesis of aluminium heterocycles with high atom economy. This strategy involves an effective cycloaddition of a free carbazolyl-aluminylene with unsaturated hydrocarbons, followed by facile cleavage of the N-Al bond. The aluminylene formally behaves as an [Al+] cation transfer reagent in a two-step manner, and the only byproduct is a carbazolide salt that can be utilized to regenerate the aluminylene. The carbazolyl Al-heterocycles show unique luminescent properties, one of which exhibits dual emission. Our approach not only has a significant impact on the future design of single-atom addition reactions, but also paves the way for emissive materials based on Al-heterocycles.

Free Aluminylenes: An Emerging Class of Compounds

“…[20] Compound 2 has proved to be a potent synthon for Alheterocycles (Figure 4). [52] It underwent a facile [4 + 1] cycloaddition reaction with 2,3-dimethyl-1,3-butadiene to produce 9. Moreover, alumole derivatives 10 and 11 were synthetically accessible upon treating 2 with an excess amount of internal alkynes.…”

“…[5,18] Free aluminylenes are capable of activating inert chemical bonds via oxidative insertion into saturated and unsaturated bonds. [19,[51][52] With a lone pair and two empty p orbitals on Al, featuring electron donating and doubly electron accepting properties, free aluminylenes can function as versatile Al ligands in coordination chemistry. [20] Most strikingly, 2 is a synthon for accessing an acyclic mono-base-stabilized aluminylene.…”