Thiolene dioxides synthesis

Thio-Claisen rearrangement 746-748 Thioketene 5-oxides photolysis of 878 reactions of 277 Thiolane dioxides formula of 382 NMR spectra of 460 reactions of 604 synthesis of 461 Thiolane oxides 747 formula of 382 IR spectra of 461 synthesis of 461, 462, 752 Thiolanes, photolysis of 881 Thiolene dioxides formula of 382 NMR spectra of 460 reactions of 464, 465 synthesis of 461 Thiolene oxides formula of 382 synthesis of 461, 746 Thiols... 

Five membered ring sulfones (thiolene-1, 1-dioxides, sulfolenes or dihydrothiophene-1, 1-dioxides) can be obtained by peracid oxidation of tetrahydrothiophene. The extrusion of sulfure dioxide from dihydrothiophene-1,1 dioxides or sulfolenes like (178) has been much studied as it provides a synthetic route to dienes, e.g. butadiene (152) (Scheme 70). The reverse reaction provides a method of synthesis of sulfolene (178) from butadiene (152) and sulfur dioxide. Thiolene dioxides or sulfolenes can be generally prepared by addition of sulfur dioxide to conjugated dienes for example, 1,4-dimethylbutadiene (179) in the presence of sulfure dioxide, triethylamine and formic acid affords 2,5-dimethylsulfolene (180) (Scheme 71). 

Since sulfoxides and sulfones are versatile synthetic intermediates, and since in both the thiolene oxide and dioxides the reverse dethionylation114 ( — SO), and cheletropic extrusion of sulfur dioxide296, respectively, readily take place thermally, these cycloadditions are expected to find a useful place in organic synthesis. It should be kept in mind, however, that the retrograde SO-diene reaction and interconversion of the thiolene oxides compete effectively against SO extrusion on heating, and that diene isomerization accompanies the forward reaction (SO + diene). 

Thiolene 1,1-dioxides and thiolane 1,1-dioxides in synthesis of biologically active compounds 85MI9. 

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