Diphenylsilanediol and Related Anticonvulsant Silicon Compounds

According to the rule of Erlenmeyer, compounds of type 43a with two hydroxyl groups bound to the same carbon atom are not stable and prefer to transform into ketones. The very few organic geminal diols that are isolable are those which carry strongly electron-attracting substituents at the carbon atom. 

However, analogous diorganosilanediols 43b are relatively stable compounds. For example, diphenylsilanediol (44), having no carbon analogue, is an isolable crystalline compound, which is easy to prepare by hydrolysis of diphenyldichlorosilane, diphenyldialkoxysilanes, and other diphenyl-substituted hydrolyzable silanes. 44 was synthesized for the first time by Kipping as early as 191263). 

The action of 44 appears to be similar to that of the anticonvulsant diphenyl-hydantoin (45). Attempts have been made66) to correlate the stereochemical and biological features of 44 with those of chemically different anticonvulsants such as diphenylhydantoin, diazepam, procyclidine, trihexyphenidyl, and ethylphen-acemide. 

Several silicon compounds related to the structure of 44 have also been found to be active in the mouse electroshock test. Some examples are given in Table 8. 

Compound ED50 for protection lmg/kg] Time after dosing [hours]  

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