A Novel Cycloaddition Reaction of Thermally Generated Sulfenes


  • Ulrich Burger
  • Serge P. Schmidlin
  • Jiri Mareda
  • Gerald Bernardinelli




The highly strained γ-sultine 4, resulting from the addition of SO2 to benzobenzvalene, is shown to undergo a thermal cycloreversion which gives 1H-indene-1-thiocarbaldehyde dioxide (6) as an intermediate and subsequently 1H-indene-1-carbaldehyde (5). The sulfene can be intercepted with electron poor C=C bonds in a cycloaddition process leading to a five-membered ring. The structure of the fused heterocyclic product 8b resulting from addition of the sulfene 6 to N-phenyl-maleimide was ascertained by X-ray analysis. Pent-4-enethial dioxide (12) produced by a sulfo-Cope rearrangement from allyl vinyl sulfone (11) is found to add to N-phenylmaleimide in the same 1,3-dipolar fashion as the sulfene 6. The cycloadditions need not be via concerted pathways.




How to Cite

U. Burger, S. P. Schmidlin, J. Mareda, G. Bernardinelli, Chimia 1992, 46, 111, DOI: 10.2533/chimia.1992.111.