Cyclic 2-thiomethyl-5-amidofurans possessing tethered pi -bonds were prepar
ed by a dimethyl(methylthio) sulfonium tetrafluoroborate (DMTSF) induced cy
clization of various amido dithioacetals. Upon heating, these systems under
go an intramolecular 4+2-cycloaddition reaction. The initially formed Diels
-Alder cycloadduct further rearranges by ring opening of the oxygen bridge
followed by a subsequent 1,2-thiomethyl shift. (C) 2000 Elsevier Science Lt
d. All rights reserved.