Disilenes regiochemistry

These E-Z isomerization studies of disilenes indicate that the n overlap between two 3p orbitals of silicon is sufficiently effective to retain the configuration around the double bond, although the 7r bonding of disilenes is significantly weaker than that of the C=C double bond. Therefore, it is expected that if appropriately substituted disilenes can be generated, regiochemistry as well as diastereochemistry of addition reactions to disilenes can be investigated even with transient reactive disilenes. 

After similar irradiation of a mixture of 20 and ethanol in a mixed matrix of 3-MP and isopentane (4 1) at 77 K, GC-MS analysis of the solution showed the formation of the expected ethanol adduct of the disilene. The regiochemistry of the product will be discussed in the next section. 

Generation of various phenyl-substituted disilenes by the photolysis of the masked disilenes, 7,8-disilabicyclo[2.2.2]octadiene derivatives, is quite useful, especially for unsymmetrically substituted disilenes. Investigation of the regiochemistry as well as the diastereochemistry of alcohol addition to phenyltrimethyldisilene was made possible for the first time by using this method27. 

---