1: ethyl (5-chlorobenzo[b]thiophen-3-yl)methyl(methyl)phosphinate With lithium hexamethyldisilazane in tetrahydrofuran T=-20 - 10°C; Inert atmosphere; 2: carbon dioxide in tetrahydrofuran T=-10 - 20°C; Inert atmosphere; 3: With hydrogenchloride in tetrahydrofuran T=4°C; Product distribution / selectivity;