1: [4-chloro-3,6-difluoro-2-(methoxymethoxy)phenyl]trimethylsilane With 2,2,6,6-tetramethyl-piperidine; n-butyllithium in tetrahydrofuran; hexane T=-75°C; 2 h; 2: carbon dioxide in tetrahydrofuran; hexane 3: With hydrogenchloride pH=1;