Asymmetric Reactions. III. The Asymmetric Synthesis of Methyl 2-Phenylpropionate in the Presence of Chiral Polymers

The asymmetric addition of methanol to phenylmethylketene was carried out in the presence of a chiral polymer obtained by the co-polymerization of N-benzyl-2-pyrrolidinylmethyl acrylate with methyl acrylate. The products obtained for the above co-polymer showed a correlation between logkR⁄kS and 1⁄T deviating from linearity, while those for poly(N-benzyl-2-pyrroIidinylmethyl acrylate) exhibited a linear relationship. N-Benzyl-2-pyrrolidinylmethyl butyrate, hexanoate, and stearate were also used as catalysts; they showed asymmetric efficiencies intermediate between those of N-benzyl-2-pyrrolidinylmethyl propionate and poly(N-benzyl-2-pyrrolidinylmethyl acrylate). The use of several high- and low-molecular-weight catalysts derived from cinchonine was similarly attempted in order to examine the polymer effect with regard to the stereoselectivity.