Oligomerization of Silyl Ketene: Favoring Chain Extension over Backbiting

Abstract

Silyl ketenes provide an interesting class of molecules to be used as building blocks for highly functional molecules and materials, including as monomers in chain growth polymerizations, whereas previous work suggests that both the carbon–carbon and carbon–oxygen double bond of silyl ketenes can undergo polymerization; no selectivity was observed and secondary reactions occurred. Herein, we report the oligomerization of tert-butyldiphenyl silyl ketene, in which polymerization of the carbon–carbon double bond is accompanied by a Brook rearrangement to give a polysilyl enol ether structure. Computational studies support that this oligomer has a rigid rod structure and is highly polarizable, which is of potential value as a dielectric material. Experimentally, the impact of initiator, solvent, and reaction time is evaluated, and product identity is verified by 2D nuclear magnetic resonance studies. In the presence of a solvent and extended reaction times, intrachain backbiting occurs to yield two cyclic sma...