-Trichlorosilylstyrene oligomers

Under cationic conditions using triflic acid as the initiator, it is possible to oligomerize β-trichlorosilylstyrene 2 to low molecular weight oligomers 14 with a maximum degree of polymerization of about 9. Termination of the process was shown to occur by an intramolecular Friedel–Crafts reaction, leading to highly functionalized, indane-terminated oligomers 9, 12, etc. At lower temperatures, the reaction is diastereoselective. The oligomerization process was shown to require electron-withdrawing groups on silicon; the replacement of Cl spectator ligands with alkoxy or alkyl groups led to protiodesilylation. The mechanism for formation of the indane-terminated oligomers is discussed. Keywords: cationic polymerization, β-silylstyrene, stereoselective oligomerization, indene termination.