Silanones from silanethiones

The adducts 41 from 1 and ketones or thiobenzophenone undergo interesting photochemical cycloreversion to afford a silanone or silanethione intermediate 42 in addition to silene 43 both of these intermediates are trapped by ethanol, as shown in Eq. (14).68 71 In the reaction with the thiobenzophenone adduct 41 (R = Ph, X = S), the intermediate silene 43 (R = Ph) was detected by Si NMR.71... 

In 1989 Jutzi and coworkers reported the reaction of decamethylsilicocene 41 with tri- -butylphosphine selenide in benzene at room temperature leading to almost quantitative formation of 1,3,2,4-diselenadisiletane derivative 138, a head-to-tail [2 + 2] cycloaddition reaction product of the initially formed silaneselone 137. The intermediacy of silaneselone 137 was supported by the fact that the reaction in the presence of 2,3-dimethyl-l,3-butadiene resulted in the formation of the corresponding [2-1-4] cycloaddition reaction product 139 (Scheme 41). As in the cases of silanone 44 and silanethione 80, the ligands on silicon undergo a haptotropic rearrangement from jj -CsMes in 41 to ij -CsMes in 138 or 139. Apparently, silaneselone 137 is not kinetically stable enough to be isolated under normal conditions. 

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