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beta-arylsulfonyl vinylketones have been shown to react, both inter acid in
tramolecularly, with 1,1-disubstituted dienes to afford depending on the us
ed -i.e. thermal or Lewis-acid catalysed-conditions, either [4+2] or [2+2]
cycloadducts, respectively. (C) 1999 Elsevier Science Ltd. All rights reser
ved.