1: N-tert-butoxycarbonyl-L-alanine With 1,1'-carbonyldiimidazole in tetrahydrofuran T=20°C; Claisen Condensation; 2 h; Inert atmosphere; 2: mono-methyl malonate potassium salt With magnesium chloride in tetrahydrofuran T=20°C; Claisen Condensation; 24 h; Inert atmosphere; Overall yield = 91 percent; Overall yield = 2.23 g;

1: tetrahydrofuran / 0.5 h / Ambient temperature 2: MgCl2 / tetrahydrofuran / 50 °C View Scheme

1: N-tert-butoxycarbonyl-L-alanine With 1,1'-carbonyldiimidazole in tetrahydrofuran Acylation; 2: mono-methyl malonate potassium salt With magnesium chloride in tetrahydrofuran Acylation; decarboxylation;

Lewis acid 1.) THF, RT, 1 h, 2.) 40-45 deg C, 6 h; Yield given;

1,1'-carbonyldiimidazole 1.) THF, r.t., 1 h, 2.) THF, r.t., 14 h; Yield given. Multistep reaction;