To a solution of 2′-amino-1′-benzyl-6-bromo-2-phenylspiro[chroman-4,4′-imidazol]-5′(1′H)-one (17.3 mg, 0.04 mmol) in 1,4-dioxane (1.5 mL) there is added Cs2CO3 (excess), 3-cyanophenylboronic acid (excess), and catalytical amount of PdCl2dppf. After degassing, the resulting mixture is heated in a CEM microwave reactor at 130° C. for 30 min Solvent is removed in vacuo and the residue is purified by reversed phase HPLC to give 3-((2R,4R)-2′-amino-1′-benzyl-5′-oxo-2-phenyl-1′,5′-dihydrospiro[chroman-4,4′-imidazole]-6-yl)benzonitrile (6.0 mg, 33%) as a TFA salt (135a) and 3-((2S,4R)-2′-amino-1′-benzyl-5′-oxo-2-phenyl-1′,5′-dihydrospiro[chroman-4,4′-imidazole]-6-yl)benzonitrile (0.86 mg, 4.8%) as a TFA salt. (135b).
