5-(2-Methoxy-ethyl)-4-methyl-thiophene-2-sulfonic acid amide (0.063 g, 0.373 mmol) was dissolved in 2.2 mL of abs. acetonitrile and treated successively with phenyl chloroformate (0.058 g, 1.0 eq.) and triethylamine (0.129 mL, 2.5 eq.), and the mixture kept at ambient temperature for 1 h. The below prepared N-(2-fluoro-ethyl)-4-methylsulfanyl-pyridine-2,6-diamine (0.094 g, 1.0 eq.), dissolved in a tiny amount of acetonitrile, was then added, and the mixture heated to 60° C. for 18 h. Cooling, pouring onto crashed ice, twofold extraction with AcOEt, washing with water and brine, drying over sodium sulfate, and evaporation of the solvents, followed by flash chromatography (SiO2, hexane/AcOEt=4/6) and crystallization from AcOEt, yielded eventually 0.041 g of the title compound as off-white crystals.
