Polymer-Supported Quinuclidinyl Catalysts for Synthesis of Cyclopolymerizable Monomers via the Aldehyde−Acrylate Coupling Reaction

With an appropriate amine catalyst, formaldehyde addition to acrylates results in α-hydroxymethyl acrylate intermediates that undergo a further condensation reaction to provide ether-linked 1,6-diene monomers capable of efficient cyclopolymerization. While 1,4-diazabicyclo[2.2.2]octane (DABCO) is an effective catalyst in the synthesis of these cyclopolymerizable monomers, a series of polymer-supported amine catalysts were prepared and evaluated in an effort to further simplify this process. 3-Quinuclidinol was reacted with methacrylic anhydride to give the functionalized methacrylate monomer, which was copolymerized with methyl methacrylate and triethylene glycol dimethacrylate. Various polymerization techniques (bulk, solution, and suspension) were used to produce the cross-linked polymeric catalysts. Supports with mole fractions of catalyst ranging from 20% to 98% were examined. In reactions with ethyl acrylate and paraformaldehyde, certain polymer-supported catalysts gave near quantitative conversion to products. The rate of reaction with the polymeric catalysts was less than that of reactions with DABCO or other nonpolymeric model catalysts; however, after reaction times of 20 h, product yields and distributions were quite similar. With the polymeric catalysts, product isolation required only simple filtration or a solvent wash rather than an aqueous extraction step. This technique was also applied to the preparation of cyclopolymerizable resins containing multifunctional oligomers.