Friedel-crafts peralkylation of benzene with omega-chloroalkyltrichlorosilanes: One-pot synthesis of polyfunctionalized hexakis[omega-(trichlorosilyl)alkyl]benzenes

Hexakis [omega-(trichlorosilyl)alkyl] benzenes 2 [alkyl = ethyl (a), propyl (b)] containing 18 peripheral chlorine substituents on the six silicon atoms as functionalities were prepared in 72% and 53% yields by the one-pot reaction of benzene with a 6-fold excess of omega-chloroalkyltrichlorosilanes such as 2-chloroethyltrichlorosilane (1a) and 3-chloropropyltrichlorosilane (1b) in the presence of aluminum chloride, respectively. Single-crystal X-ray analysis of compound 2b reveals that the 18 chlorine substituents on the six silicons are symmetrically located on the outside. Compounds 2a,b reacted easily with methylinagnesium bromide in diethyl ether at room temperature to give hexakis[omega-(trimethylsilyl)alkyl] in high isolated yields of 93 and 94%.close1