Siloxanes Tetrasiloxanes, Trisiloxanes

The unique hormonal activity of siloxanes is limited to methylaryl-substituted, linear di- and trisiloxanes and cyclic tri- and tetrasiloxanes (67, 75, 76, 81). In general, at least one arylsilicon grouping is necessary for activity. The substitution of an alkyl group for a phenyl group either decreases the activity markedly or eliminates it entirely. Cyclosiloxanes... 

The Si-H functions of the ferriomethyl-siloxanes 19a-c offer the possibility for further functionalization reactions. For example, photochemical treatment induces elimination of CO and subsequent reaction steps leading to rearrangement of the siloxane backbone. In the case of the ferriomethyl-tri- and -tetrasiloxanes 19a,c, UV irradiation in benzene results in the formation of the six-membered cyclo(ferra)trisiloxanes 20a,b (Scheme 26.1). ... 

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