Fine tuning of the [2+2] vs [4+2] selectivity of 1,1-disubstituted dienes in cycloaddition reactions

Article abstract of DOI:10.1016/S0040-4039(99)01884-5

β-Arylsulfonyl vinylketones have been shown to react, both inter and intramolecularly, with 1,1-disubstituted dienes to afford, depending on the used -i.e. thermal or Lewis-acid catalysed-conditions, either [4+2] or [2+2] cycloadducts, respectively.