The diels-alder reactivity of some new sulfur (selenium) substituted halobutadienes

Abstract 3-PhS(e)-(1),2-(di)halobutadienes undergo BF 3 catalysed cycloadditions with methyl vinyl ketone at 25°C, to give good yields of adducts in which the regiochemistry of addition is mainly controlled by the sulfur (selenium) atom.