A novel group transfer polymerization of 1‐trimethylsiloxy‐benzocyclobutene via hetero Diels‐Alder reaction

A novel group transfer polymerization via hetero‐Diels‐Alder reaction is described. When 1‐trimethylsiloxybenzocyclobutene ( 1 ) was treated with a catalytic amount of p ‐anisaldehyde (4‐methoxybenzaldehyde) and TASF (tris(dimethylamino)sulfonium difluorotrimethylsilanide) at room temperature for 0.5 h, poly[1,2‐phenylene‐1‐(trimethylsiloxy)ethylene] was obtained quantitatively. The number‐average molecular weight of the polymer was M̄ n = 2000 and the molecular weight distribution was narrow (ratio of weight‐to number‐average molecular weights M̄ w /M̄ n = 1.18). Structural characteristics suggested a polymerization mechanism involving isomerization of 1 to o ‐quinodimethane and successive hetero‐Diels‐Alder reaction leading to poly[1,2‐phenylene‐1‐trimethylsiloxy ethylene]. The living‐like nature of the polymerization was supported by a monomer addition experiment in which the molecular weight increased according to the increase of the added monomer.