To a solution of 444 mg (3.0 mmol) 6-cyano-nicotinic acid and 354 mg (3.5 mmol) N-methylmorpholine in 7 ml DMF at −20° C. was added 450 mg (3.3 mmol) isobutyl chloroformate. The reaction mixture was warmed to 5° C., and 625 mg (3.0 mmol) mono-boc-ortho-phenylenediamine was added. The reaction mixture was warmed to rt overnight and then poured into 50 ml 5% aqueous citric acid. The aqueous phase was extracted with ethyl acetate, the combined organic phases were washed with bicarbonate and brine and dried over Na2SO4. The solvent was evaporated and the residue was subjected to silica gel chromatography (petrol ether/ethyl acetate 2:1) to yield 795 mg (2.35 mmol) {2-[(6-Cyano-pyridine-3-carbonyl)-amino]-phenyl}-carbamic acid t-butyl ester; mp.183–184° C.
