A mixture of (2R)-2-hydroxypropanamide (0.29 g, 3.3 mmol) and triethyloxonium tetrafluoroborate (0.61 g, 3.2 mmol) in THF (5.6 mL) was stirred at room temperature for 2 h. The solvent was removed and the residue dissolved in ethanol (2.4 mL) and added to a suspension of tert-butyl ({trans-4-[(6-aminothieno[3,2-b]pyridin-7-yl)amino]cyclohexyl}methyl)carbamate (0.30 g, 0.80 mmol) in ethanol (8.6 mL). The mixture was stirred at 85° C. for 2 h. The mixture was concentrated and purified with flash chromatography (0-10% methanol/dichloromethane) to give the desired product (0.21 g, 61%). LCMS calculated for C22H31N4O3S (M+H)+: m/z=431.2. Found: 431.1.
