1: (+/-)-methylenecyclopropanecarboxylic acid With triethylamine; isobutyl chloroformate in tetrahydrofuran T=0°C; 0.25 h; 2: diethylamine in tetrahydrofuran T=20°C; 12 h; Further stages.;

1.1: 80 percent / NaH / diethyl ether 2.1: 91 percent / K2CO3 / methanol; H2O 3.1: isobutylchloroformate; triethylamine / tetrahydrofuran / 0.25 h / 0 °C 3.2: 96 percent / tetrahydrofuran / 12 h / 20 °C View Scheme

1.1: 91 percent / K2CO3 / methanol; H2O 2.1: isobutylchloroformate; triethylamine / tetrahydrofuran / 0.25 h / 0 °C 2.2: 96 percent / tetrahydrofuran / 12 h / 20 °C View Scheme