1: (3,4,5-trimethoxyphenyl)acetic acid ethyl ester With lithium diisopropyl amide in tetrahydrofuran T=-78°C; 1 h; 2: [(Cyanocarbonyl)oxy]ethane in tetrahydrofuran T=-78 - 20°C;

copper(l) iodide; caesium carbonate in 1,4-dioxane T=25°C; 28 h;

1.1: (COCl)2; DMF / tetrahydrofuran / 0.17 h 2.1: LDA / tetrahydrofuran / 1 h / -78 °C 2.2: 87 percent / tetrahydrofuran / -78 - 20 °C View Scheme

1.1: LDA / tetrahydrofuran / 1 h / -78 °C 1.2: 87 percent / tetrahydrofuran / -78 - 20 °C View Scheme