5-(3-chloro-4-cyanophenyl)-1H-pyrazole-4-carbonitrile (0.9 g, 3.94 mmol) dissolved in dry THF (15 ml), (S)-tert-butyl 1-hydroxypropan-2-ylcarbamate (0.690 g, 3.94 mmol) and triphenyl phosphine (1.549 g, 5.90 mmol) dissolved in dry THF (15 ml) were loaded into a flask and cooled to 0° C. with an ice bath. Di-tert-butyl azodicarboxylate (1.360 g, 5.90 mmol) was added slowly and stirred for 10 min while keeping the temperature at 0° C. The temperature was allowed to rise to RT and the mixture was stirred overnight. Next day the mixture was evaporated and the intermediate deprotected by adding 10% HCl/EtOH solution (40 ml) and stirring overnight at RT. The mixture was again evaporated and the residue extracted with DCM/water. The pH of aqueous phase was adjusted to 12 by adding 2 M NaOH and extracted again with DCM. The organic phase was isolated with phase separator and evaporated. The product was used in the next step without further purification. 1H-NMR (400 MHz; DMSO-d6): δ 1.14 (d, 3H), 4.27-4.39 (m, 3H), 6.50 (s, 2H), 8.02 (dd, 1H), 8.15-8.19 (m, 2H), 8.79 (s, 1H).
