1: 1-allyl-3-bromo-2-methoxymethoxybenzene With tert.-butyl lithium in tetrahydrofuran; pentane T=-78°C; 1.5 h; 2: carbon dioxide in tetrahydrofuran; pentane T=-78°C; 1.5 h; 3: With hydrogenchloride in tetrahydrofuran; pentane T=20°C;