New polyunsaturated organosilicon dendrimers based on 1,1-diethynyl-and 1-vinyl-1-ethynylsilacycloalkanes

1,1-Dichloro-and 1-vinyl-1-chlorosilacyclanes were prepared by reactions of tetrachlorosilane or vinyltrichlorosilane with magnesium and 1,4-dibromobutane or 1,5-dibromopentane. The reactions of the products obtained with ethynylmagnesium bromide or bis(bromomagnesio)acetylene yield the corresponding ethynylsilacyclanes. Condensation of 1,1-diethynylsilacyclanes or bis(ethynylsilacyclopentyl)ethyne with an equimolar amount of ethylmagnesium bromide and methylbis(trimethylsilylethynyl)fluorosilane gave the corresponding highly unsaturated mono-and binuclear first-generation dendrimers with the cores formed by the silicon atoms incorporated in silacycloalkane fragments. The ¹H, ¹³C, and ²⁹Si NMR spectra of all the compounds obtained were studied. The key parameters and the chemical graph of the new dendrimers are presented.