Thiirene oxides photolysis

Diphenyl thiirene oxide 151 is a surprisingly thermally stable compound, whose chemistry was described in 1979 [67], Photolysis near room temperature yields diphenyl acetylene in nearly quantitative yield. Whether this extrusion is concerted or stepwise and the state of the eliminated SO awaits further investigation. 

Thiirenes have been isolated in argon matrices at 8 K by photolysis of 1,2,3-thiadiazoles or vinylene trithiocarbonates (Scheme 151) (80PAC1623, 8UA486). They are highly reactive and decompose to thioketenes and alkynes (Scheme 22). Electron withdrawing substituents stabilize thiirenes somewhat, but no known thiirene is stable at room temperature unlike the relatively stable thiirene 1-oxides and thiirene 1,1-dioxides. 

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