Peracid oxidation and photooxygenation reactions of silacyclopentadienes

Electrochemical oxidation of silacyclopentadienes (siloles)

“…It is noteworthy that this type of rearrangement is known [29,30] when singlet oxygen reacts with 1,1-dimethyl-2,3,4,5-tetraphenyl-1-silacyclopentadiene, as described in Scheme 4. However, irradiation of 1-methyl-vinyl-2,3,4,5-tetraphenyl-1-silacyclo-pentadiene under a stream of air gave a mixture of oxygenated products, including 1 and its dihydro derivative, but no product containing a silicon atom was detected [5].…”

“…In some cases, as for products 1, 2 and 4, authentic samples have been used for characterization. Some of the products were compared with available literature spectral data [5]. Mass spectra ( …”

“…Numerous chemical reactions have been reported for silacyclopentadiene, including those with halogens, acids, bases, alcohols, Grignard and lithium reagents, and cycloaddition [4]. Oxidation of 1-methyl-1,2,3,4,5-pentaphenylsilole with perbenzoic acid afforded a mixture of at least seven products, resulting from ring-opening, other bond cleavages, as well as rearrangements [5]. Photooxygenation of 1,1-dimethyl2,3,4,5-tetraphenyl-1-silacyclo-pentadiene led to dibenzoylstilbene and 3,3-dimethyl-1,5,6,7-tetraphenyl-2,4-dioxa-3-silabicyclo[3.2.0] heptene [6,7].…”

Electrochemical oxidation germacyclopentadienes (germoles)

“…Yields were determined by GLC traces compared also with dibenzoylstilbene as internal standard. Some of the products were compared with available literature spectral data [24,25]. Mass spectra ( …”

“…Also, one cannot rule out other mechanisms for the formation of some of the products described in Scheme 2. For example, silacyclopentadienes are known [25] to undergo epoxidation on treatment with peracids, which are transformed further to products 1-4 by acid catalysis. Previously, we reported the involvement of molecular oxygen in the electrochemical oxidation of cyclic polysilanes [16][17][18].…”