Friedel−Crafts Alkylation of Polychlorobenzenes with (1,2-Dichloroethyl)trichlorosilane

Abstract

(1,2-Dichloroethyl)trichlorosilane (2) reacted with a 6-fold excess of mono-, di-, and trichlorobenzenes at 120 °C in the presence of aluminum chloride to give regiospecific (2,2-diarylethyl)trichlorosilanes via a carbocation rearrangement. The yields were 61−69%, and regioisomers of (1,2-diarylethyl)silanes were not obtained. Alkylation of 1,2,3,4-tetrachlorobenzene with 2 did not give [2,2-bis(tetrachlorophenyl)ethyl]trichlorosilane or 9,10-bis(silyl)methyl-9,10-dihydroanthracenes but gave cyclic silyl-substituted indanes in 84% yield via the acid-catalyzed dimerization of β-(trichlorosilyl)styrene formed by the first alkylation, followed by dehydrochlorination. The structure of 1,2-trans-2,3-trans-4,5,6,7-tetrachloro-1-(2,3,4,5-tetrachlorophenyl)-2-(trichlorosilyl)-3-((trichlorosilyl)methyl)indane has been determined by X-ray crystallography. The desilylated product, 1,3-cis-4,5,6,7-tetrachloro-1-(2,3,4,5-tetrachlorophenyl)-3-((trichlorosilyl)methyl)indane, was reduced by LiAlH4, and its structure was also determined.

Friedel−Crafts Peralkylation of Benzene with ω-Chloroalkyltrichlorosilanes: One-Pot Synthesis of Polyfunctionalized Hexakis[ω-(trichlorosilyl)alkyl]benzenes

“…Although the reaction generally proceeds in good yield in each step, the overall yields are low. 1a,2b, Furthermore, it is difficult to isolate such compounds from their reaction mixtures. As one synthetic approach, simple organosilicon compounds containing many chlorine substitutents on a silicon are used as starting materials for the preparation of advanced and polyfunctionalized molecules through the repeated reactions of both alkenylation with alkenylmetal reagents and hydrosilylation with hydrosilanes in sequence. 1a,2a,b, For the preparation of organosilicon compounds with Si−Cl functionalities, we have studied the alkylation of aromatic compounds with organosilicon compounds such as alkenylchlorosilanes and (chloroalkyl)chlorosilanes, which were catalyzed by Lewis acid. In a series, the peralkylation of benzene with excess vinylchlorosilanes in the presence of aluminum chloride has been conducted in order to prepare symmetric and polyfunctionalized compounds.…”