Thiirane 1,1-dioxides sulfoxides, cyclic

A unique characteristic feature of the cyclic three-membered ring sulfones and sulfoxides is the dramatic increase in the length of the carbon-carbon single bonds and the carbon-carbon double bonds in the series of thiirane-thiirane oxide-thiirane dioxide (20a -> 16a -> 17a), and thiirene-thiirene oxide-thiirene dioxide (21 -> 18a -> 19b). 

Thiirane A-oxides are effective precursors for sulfur monoxide (SO) under thermal conditions <1997JOC8366>. The sulfur monoxide has been trapped by a variety of dienes to form cyclic sulfoxides. Extmsion of SO2 from thiirane A,A-dioxides to form alkenes under thermal conditions is well known. The reaction takes place readily at room temperature in the presence of KO/-Bu in tetrahydrofuran (THF). It constitutes the final step of the Ramberg-Backlund rearrangement <20030R357, 1999CC217>. 

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