1: With trimethylsilyl trifluoromethanesulfonate in dichloromethane T=-70°C; Addition; 6 h; 2: With water in dichloromethane T=20°C; Hydrolysis; 0.5 h; 3: With water; sodium hydrogencarbonate in dichloromethane T=20°C; Hydrolysis; 0.5 h;

1: With trimethylsilyl trifluoromethanesulfonate in dichloromethane T=-70°C; Addition; 6 h; 2: With water in dichloromethane T=20°C; Hydrolysis; 0.5 h; 3: With water; sodium hydrogencarbonate in dichloromethane T=20°C; Hydrolysis; 0.5 h;

1: (E)-3-ethoxy-crotonic acid ethyl ester With lithium diisopropyl amide in tetrahydrofuran; hexane T=-70°C; 2.5 h; 2: (1S,2R,4R,SS)-7,7-dimethyl-N-(phenylmethylene)-2-(trimethylsilyloxy)bicyclo[2.2.1]heptane-1-methanesulfinamide in tetrahydrofuran; hexane T=-30°C; 3.5 h; 3: With hydrogenchloride in ethanol; dichloromethane T=20°C; 24 h; Title compound not separated from byproducts;