Elimination of Silicon Compounds

Literature reports concerning the metabolism of organosilicon compounds are sparse. The information available indicates a rather normal detoxification pattern, as long as the chemical characteristics of silicon are taken into account. 

However, most organosilicon compounds are metabolized after ingestion or injection, and their metabolites are eliminated. For example, silameprobamate (27) undergoes to - 1 hydroxylation, following the same pattern as meprobamate itself. The difference in the metabolism of the two compounds is that the silicon compound also undergoes silicon-carbon cleavage to yield a silanol that can be isolated from the urine as a disiloxane (32) see Eq. (1). 

Phenylsilanes (PhSiRs) undergo in vivo hydroxylation at the para position (706), as shown in Eq. (2). This is a common detoxification pathway 

The silicon-hydride group is rapidly oxidized to a silanol group in vivo, according to one report (106). The silanol was isolated as the elimination product see Eq. (3). 

This instability of silicon hydrides is not surprising in the laboratory these compounds are excellent reducing agents. However, the instability of the Si—H bond is disappointing because of the limitations it places on preparing silicon analogs of active carbon compounds. Most C—H bonds are stable in vivo, but a compound having a Si—H bond would be readily detoxified and eliminated. 

---

Homoallylstannanes are also potential starting materials for cyclopropanes. Selective addition of electrophiles to but-3-enyltin compounds leads to a y-methyl ion which then undergoes destannylation to give cyclopropylmethyl derivatives 11 in moderate to high yield. This reaction is mechanistically similar to the methyl ion induced 1,3-eliminations of silicon compounds. 

---