Cationic Monomer-Isomerization Polymerization of Oxetanes Having an Ester Substituent, to Give Poly(orthoester) or Polyether

Atom Transfer Radical Polymerization of 3-Ethyl-3-(acryloyloxy)methyloxetane

“…The intense peak at 1730 cm -1 attributed to ester group is also not affected in PEAO. Corey and Raju 28 reported that oxetane esters on treatment with boron triflouride etherate at -15 °C was converted to isomeric bridged ortho esters by intramolecular rearrangement between the ester and the oxetane group. Recently, Kanoh et al 29 reported the cationic isomerization of oxetane rings bearing an ester group in the presence of a Lewis acid and subsequent polymerization of the isomerization product to yield poly(ortho ester)s or polyethers.…”

“…The intense peak at 1730 cm -1 attributed to ester group is also not affected in PEAO. Corey and Raju reported that oxetane esters on treatment with boron triflouride etherate at −15 °C was converted to isomeric bridged ortho esters by intramolecular rearrangement between the ester and the oxetane group. Recently, Kanoh et al .…”

Coordinate anionic ring‐opening polymerization of oxetanes with aluminum benzyl alcoholate bis(2,6‐di‐tert‐butyl‐4‐methylphenolate)

“…Our interest was focused on the mechanistic aspect of the polymerization with BnOAD. The Lewis acidity of BnOAD and MAD could be qualitatively estimated from the acid‐catalyzed isomerization of (3‐methyloxetan‐3‐yl)methyl benzoate leading to the bicyclic orthoester (Scheme ): the intramolecular nucleophilic attack of the ester carbonyl group was always preferred to the intermolecular nucleophilic attack of the oxetanyl group (ring‐opening polymerization) 4, 15. These organoaluminum complexes had insufficient Lewis acidity to bring about the isomerization.…”

“…OxOH was esterified with benzoyl chloride in the presence of anhydrous Et 3 N in CH 2 Cl 2 4. Ordinary extractive workup gave the crude ester, which was purified by distillation from CaH 2 under reduced pressure to give (3‐methyloxetan‐3‐yl) methyl benzoate in a 66% yield.…”

“…Thus, the cationic ring‐opening polymerization of substituted oxetanes proceeds smoothly by the active chain‐end mechanism,1 almost regardless of pendant functional groups and their bulkiness. In addition, we have recently found that the cationic isomerization polymerization of oxetanes with a carbonyl functional group, such as imide, amide, and ester, gives unusual polymers with cyclic structures in the main chains3, 4 because of the neighboring group participation of the carbonyl group.…”