n-butyllithium; sodium hydride in tetrahydrofuran; hexane; paraffin 3 h; Ambient temperature;

1: acetic acid tert-butyl ester With N,N,N',N',N'',N''-hexamethylphosphoric triamide; n-butyllithium; diisopropylamine in tetrahydrofuran; hexane T=-78°C; 1 h; 2: pent-4-enoic acid ethyl ester in tetrahydrofuran; hexane T=-78 - 20°C; Further stages.;

1: 3-vinylpropionic acid With 1,1'-carbonyldiimidazole in tetrahydrofuran T=20°C; 1 h; 2: With n-butyllithium; diisopropylamine in tetrahydrofuran; hexane T=-78°C; 0.5 h; 3: acetic acid tert-butyl ester in tetrahydrofuran; hexane T=-78 - 20°C; Further stages.;

1: dicyclohexyl-carbodiimide; 4-(N,N-dimethlyamino)pyridine / dichloromethane / 16 h / 0 °C / |Inert atmosphere 2: 5 h / |Reflux; |Inert atmosphere View Scheme

1.1: 82 percent / NaCl / dimethylsulfoxide; H2O / 8 h / 160 - 180 °C 2.1: diisopropylamine; nBuLi; HMPA / tetrahydrofuran; hexane / 1 h / -78 °C 2.2: tetrahydrofuran; hexane / -78 - 20 °C View Scheme

5 h; RefluxInert atmosphere;