1: thiophene-2-carboxylic acid methyl ester With lithium diisopropyl amide in tetrahydrofuran; n-heptane; ethylbenzene T=-78°C; 1 h; 2: tributyltin chloride in tetrahydrofuran; n-heptane; ethylbenzene T=-78°C; 2 h; Stirring overnight at 20 C;