1: 2-Propenoic acid tert-butyl ester; cis-maleic acid With [{(η5-C5Me5)RhCl}2(μ-Cl)2]; silver carbonate in N,N-dimethyl-formamide T=140°C; 1 h; Inert atmosphere; 2: methyl iodide With potassium carbonate in N,N-dimethyl-formamide T=20°C; 3 h; Overall yield = 77 percent; Overall yield = 82 mg;