in toluene T=110 - 120°C; 4 h;

1: C12H20BNO2S With n-butyllithium; diisopropylamine in tetrahydrofuran T=-80°C; Inert atmosphere; 2: With carbon dioxide in tetrahydrofuran T=100°C; Inert atmosphere; 3: 2,3-dimethylbutane-2,3-diol Further stages;

1: thiophene-2-carboxylic acid With lithium diisopropyl amide in tetrahydrofuran; hexane T=-70 - 20°C; 2 h; 2: 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane in tetrahydrofuran; hexane T=-70 - 20°C; 12 h;