Thietane 1,1-dioxides reduction

Application of the enamine-sulfene cycloaddition allowed the synthesis of 78 and 79 from the corresponding a,/l-unsaturated amines and sulfenes. Similarly, using enamine 80, the crystalline morpholino thietane dioxides (81) were produced. Elimination via the N-oxide gave the corresponding thiete dioxide, whereas reduction by LiAlH4 yielded the thietane 82. 

The thietane dioxides can be converted into thietes by successive reduction, methyla-tion and Hofmann elimination of the resulting thietane derivatives (equation 2)18. 

Conversion of thietane 1-oxides and 1,1-dioxides back to thietanes can be accomplished with aqueous sodium bisulfite (limited to thietane 1-oxides (72JOC919)) or more generally with LAH, as illustrated for sulfoxide (189) (79JOC4757) and sulfone (190) <65LA(684)92, 69JA2796). Ring-substituted thietanes are often conveniently prepared by ring functionalization of the thietane 1,1-dioxide followed by LAH reduction, as will be illustrated below. 

Lithium aluminum hydride in ether or tetrahydrofuran reduces thietane 1,1-dioxides to This reduction was discussed in... 

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