Aryl substituted silacyclobutanes

Aryl substituted silacyclobutanes were prepared by reaction of 1,1-dichloro-1-silacyclobutane or 1-chIoro-l-methyl-1-silacyclobutane with suitable Grignard species. Aryl- and alkenyl-substituted silanes were prepared by reaction of... 

Summary From catalytic hydrogenation of olefinic silicon-functionalized compounds (chloro-Si, alkoxy-Si, alkyl-Si, and aryl-Si) the saturated products are available in good yield. In general, the chloro- and alkoxy substituents are unaffected and for silaheterocyclic compounds the cyclic or the bicyclic moieties, respectively, remain intact. Thus, the silanorbomenes 1, 2, and 3, compounds containing cyclopentenyl groups 13 and 15, and various carbon vinyl substituted silacyclobutanes 7, 8, and 11 were hydrogenated in a simple apparatus. The reactions were performed in ether and THF as solvents the hydrogenation catalyst Pd/C can be used several times. 

For 2-substitued silacyclobutanes 193 the product distribution is very much dependent on the substituent R1 104, and energetic factors (stabilization of the olefin versus the ionized silene) seem to account for this. For example, 2-alkyl-substituted silacyclobutanes 193a favour the formation of 191, while 2-aryl-substituted analogues 193b preferentially decompose to 194 (reaction 75). 

Silacyclobutane monomers with aryl and alkylaryl substituents were prepared in multi-gram quantities from reaction of commercially available 1,1 -dichloro-1 -silacyclobutane and 1 -chloro-1 -methyl-1 -silacyclobutane precursors with suitable Grignard reagents. Allyl-substituted AB and AB2 type monomers were prepared from treatment of intermediate diorganochlorosilanes and organodichlorosilanes, respectively, with allylmagnesium bromide. Selected structures of the monomers used in this work are represented in Figure 2. 

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