The intramolecular photometathesis of pyrroles.

UV irradiation of various electron deficient pyrrole derivatives induces a novel methathesis sequence resulting in selective cleavage of the 2,3-pyrrole bond. The overall sequence has been shown to proceed by two discrete wavelength-dependent steps involving sequential [2+2] cyclobutane formation followed by photochemically mediated retro-[2+2] to the products.