To a mixture of 2-(4-amino-3-cyclohex-1-enyl-phenyl)-malonic acid dimethyl ester (as prepared in the previous step, 100 mg, 0.330 mmol), potassium 4-cyano-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazole-2-carboxylate (as prepared in Example 1, step (d), 106 mg, 0.346 mmol) and bromotripyrrolidinophosphonium hexafluoro-phosphate (PyBroP) (154 mg, 0.330 mmol) in 3 mL of DMF was added N,N-diisopropylethylamine (DIEA) (0.172 mL, 0.990 mmol). After stirring at RT for 16 h, the mixture was treated with 50 mL of EtOAc and washed with H2O (2×15 mL), brine (15 mL) and dried (Na2SO4). The organic solvent was evaporated and the residue was purified by flash chromatography on silica gel (5-10% EtOAc-hexane) to give 118 mg (85%) of the title compound as a colorless oil: Mass spectrum (ESI, m/z): Calcd. for C28H36N4O6Si, 553.2 (M+H). found 552.6.
