Under nitrogen, 0.38 g (1.1 mmol) of 3-(2,2-diethoxyethyl)amino-2-methyl-4-(methyl-sulfonyl)benzoic acid, 0.16 g (1.4 mmol) of 5-hydroxy-1-methylpyrazole and 0.25 g (1.3 mmol) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride were dissolved in dry CH3CN. The mixture was stirred at RT for 1 day and allowed to stand for 2 days. 0.31 ml (2.2 mmol) of NEt3, 0.06 ml (0.4 mmol) of Me3SiCN and a spatula tip of KCN were added, and the mixture was stirred at RT for 2 days. The solvent was removed under reduced pressure, and the residue was taken up in CH2Cl2 and 10% strength H2SO4. The organic phase was removed and dried over MgSO4, and the solvent was removed under reduced pressure. The residue were purified by preparative HPLC. This gave 0.14 g of a red oil in a purity of 93%.
