Carbene-Stabilized Aluminacyclopropene-Cyclopropenylalane Rearrangement

A direct [1 + 2] cycloaddition reaction between an N-heterocyclic carbene-stabilized acyclic aluminylene and bis(trimethylsilyl)acetylene leads to the formation of neutral aluminacyclopropene, compound <bold>2</bold>. However, this compound demonstrates thermal instability in solution, resulting in an aluminacyclopropene-cyclopropenylalane rearrangement. This transformation exemplifies a formal constitutional isomerization between the C-AlC2 and Al-C-3 systems. Density functional theory computations provide insights into the mechanism behind this unique rearrangement. Our findings contribute a novel aspect to the recent observation that N-heterocyclic carbenes can act as single-carbon-atom sources.