By Cycloadditions involving Sulphenes

By Cycloadditions involving Sulphenes. The cycloaddition of sulphenes to electron-rich olefins remains a convenient method of preparing compounds with the thietan ring system. In their preparation of 3-substituted thietans, 

Barbarella, A. Garbesi, and A. Fava, Helv. Chim. Acta, 1971, 54, 2297. 

Siegl and Johnson formed 3-substituted-3-iV-morpholinothietan 1,1-dioxides by cycloaddition of sulphene to the appropriate 1-substituted- 

2- methylpropene giving only thietan 1,1-dioxide derivatives, whereas with a-morpholinostyrene only an acyclic sulphone was formed. Similarly benzoylsulphene gave no [2 + 2]cycloadducts with 1-pyrrolidinocyclo-hexene. Sulphenes are normally formed for these cycloadditions by the 

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