Metal-free entry to phosphonylated isoindoles by a cascade of 5-exo-dig cyclization, a [1,3]-alkyl shift, and aromatization under microwave heating.

[reaction: see text] When o-ethynylbenzyl alpha-aminophosphonates are heated under microwave conditions, a rearrangement occurs which results in the formation of phosphonylated isoindoles. The rearrangement consists of a 5-exo-dig cyclization followed by a [1,3]-alkyl shift and finally aromatization.