Ring extension and rearrangement reactions of an ambiphilic aluminacyclobutene.

Authors

Pascal Weisenburger, Israel Fernández, Frank Breher

Published in

Dalton transactions (Cambridge, England : 2003). Jul 27, 2026. Epub Jul 27, 2026.

Abstract

The combination of aluminum and carbon as a Lewis acid and base, respectively, to form an intramolecular Frustrated Lewis Pair (FLP) has been less explored compared to other combinations. Herein, we present the synthesis of a metallacyclic aluminum/carbon-based ambiphile and its reactivity towards carbonyl and isocyanate compounds. The aluminacyclobutene title compound Ph₃PCH(CHCSiMe₃)AltBu₂ (3) was synthesized from an alkynyl-substituted phosphonium salt [Ph₃PCH₂CCSiMe₃][Br] (2) and a diorganoalanate Li[tBu₂AlH₂]·2thf (1). The alanate 1 is structurally characterized and applied in a hydrometallation reaction. The obtained ylide-based ambiphile 3 shows typical FLP reactivity towards carbonyl compounds resulting in ring expansion, forming Ph₃PCH(CHCSiMe₃){(Ph)C(H)O}AltBu₂ (4). In the reaction with phenyl isocyanate, a rearrangement reaction of the ambiphile was observed, which led to proton migration and the formation of an AlOCN heterocycle of the composition Ph₃PC(CHCHSiMe₃){(Ph)NCO}AltBu₂ (6). The proton shuttling initially proceeds from the ylidic carbon atom to the isocyanate's nitrogen atom providing Ph₃PC(CHCSiMe₃){(PhNH)CO}AltBu₂ (5), and finally to the carbon atom originally bonded to the aluminum atom. The experimental findings were rationalized through DFT calculations including an analysis of the rearrangement mechanism.

PMID:
42504753
Bibliographic data and abstract were imported from PubMed on 27 Jul 2026.

Read full publication at:
Please sign in to see all details.

Stats

1-terrible, 9-excellent. How would you rate this publication? Sign in in to submit your rating.

Post a comment

You need to be signed in to post comments. You can sign in here.

Comments

There are no comments yet.