Methacrylic anhydride was anionically polymerized for the first time by a lithium ester enolate with the aid of the bulky aluminum bisphenoxides in dichloromethane at -78 degrees C to afford polymers consisting of six-membered cyclized units as confirmed by NMR and IR spectroscopy, while a less bulky trialkylaluminum was ineffective. At higher temperatures, no polymeric product formed partly due to the carbonyl addition reaction of the alkyl group in the aluminum compound to the monomer. From the model reactions in the presence and absence of the aluminum compounds, importance of formation of an enolate-aluminate type species is suggested. Tacticity of PMMA derived from poly(MAAn) is rich in syndiotacticity in comparison to radically prepared one. (C) 2013 Elsevier Ltd. All rights reserved.