1: trifluoromethylsulfonic anhydride; N-[(phenyl)(pyrrolidin-1-yl)methylene]benzamide in dichloromethane T=-50°C; 1.5 h; 2: ethyl DL-phenylglycinate hydrogen p-toluenesulfonate With triethylamine in dichloromethane T=20°C; 16 h; Further stages.;

1.1: CH2Cl2 / 1.5 h / -50 °C 1.2: 47 percent / CH2Cl2 / 4 h / -78 - 20 °C 2.1: 42 percent / tBuOK; nBuLi / tetrahydrofuran; hexane / 3 h / -40 °C View Scheme