Formation of Organosilicon Compounds 117:1 C-brominated 1,3,5-Trisilacyclohexanes and Their Reactions with BuLi

The photobromination of 1,1,3,3,5,5-hexamethyl-1,3,5-trisilacyclohexane (1) almost exclusively attacks CH 2 groups and results in 2,2-dibromo-trisilacyclohexane (2) as well as 2,2,4,4-tetrabromo-trisilacyclohexane (3) in high yields. Starting from a mixture of C-brominated trisilacyclohexanes the isomeric 2,2,9-tribromo-1,3,3,5,5,8,8,10,10,13,13-undecamethyl-1,3,5,8,10,13-hexasilabicyclo[7.2.2]tridec-6-yne (6) had been obtained in very low yield in an attempt to establish a preparative route to adamantanes with a C 4 Si 6 skeleton, i.e., with C bridgeheads and SiR 2 bridges. By ICl-cleavage of a Si—methyl bond in 2 and subsequent substitution with Br 3 CLi, the trisilacyclohexane 4 with functional groups in opposite positions of the ring can be obtained. Linking the step-by-step synthesized Cl-Me 2 Si-C=C-SiMe 2 -CH 2 -SiMe 2 -Ph to the CBr 3 group of 4 results after HBr-cleavage of the Si—Ph bond in (ω-bromo-octynyl)-trisilacyclohexane (12). A ring closure of 12 would result in an isomeric hexasila bicyclo[7.2.2]tridec-6-yne. The compounds were characterized by 1 H, 13 C, and 29 Si NMR spectra. Additionally, the molecular structures of 4 and 6 were confirmed by X-ray single crystal investigations.Key words: 1,1,3,3,5,5-hexamethyl-1,3,5-trisilacyclohexane, bromination, 2,2,9-tribromo-1,3,3,5,5,8,8,10,10,13,13-undecamethyl-1,3,5,8,10,13-hexasilabicyclo[7.2.2]tridec-6-yne, carbosilane synthesis, NMR data, crystal structure investigation.