1: thien-2-ylmagnesium bromide With titanium tetraethoxide in tetrahydrofuran T=20°C; 0.5 h; Inert atmosphere; 2: 2-bromo-4-pyridinecarboxylic acid With tributylphosphine; cobalt(II) chloride in tetrahydrofuran T=20°C; Inert atmosphere; chemoselective reaction;