1.3- Silyl migrations solvent effects

C in dichloromethane. Solvent effects have been observed. Thus treatment of enol ether (53) with MCPBA in ether resulted in isolation of the benzoate (54). This was considoed to arise as a result of the increased nucleophilicity of the residual carboxylic acid in ether over that in dichloromethane. Isolation of the silyloxy epoxide by an analogous ethereal oxidation suggests periugrs that the 1,4-silyl migration is intrinsically less facile in this solvent. Generally however the process is efficiem and simple substrates are readily oxygenated (Scheme 11). 

A detailed study of the photophysics and photochemistry of 2,2-diphenyl-hexamethyltrisilane (73) (Scheme 7) has been made. In polar solvents (73) exhibits an intense fluorescence attributed to intramolecular charge transfer, and this solvent effect is also reflected in the photochemistry. In non-polar solvents extrusion of diphenylsilylene and 1,3-silyl migration to give (74) are the major photoreactions but in ethanol-hexane solvolytic cleavage of the... 

The following case shows a very interesting solvent effect that was not explained by the authors, but it has been shown by others that the 3-hydroxyl is typically the kinetic product and the 2-hydroxyl is the thermodynamic product, thus implicating possible silyl migration. 

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