Oxalyl chloride → {[(R)-7-(3,5-dichloro-phenyl)-5-methyl-6-oxo-5-(4-trifluoromethoxy-benzyl)-6,7-dihydro-5H-imidazo[1,2-a]imidazole-3-carbonyl]-amino}-acetic acid tert-butyl ester

Participants

Reaction Steps

To a solution of (R)-7-(3,5-dichloro-phenyl)-5-methyl-6-oxo-5-(4-trifluoromethoxy-benzyl)-6,7-dihydro-5H-imidazo[1,2-a]imidazole-3-carboxylic acid (0.500 g, 1.0 mmol) in CH2Cl2 (15 mL) was added oxalyl chloride (0.194 mL, 2.2 mmol), followed by slow addition of DMF (0.05 mL). The reaction was stirred for 90 min. The volatiles were removed in vacuo, and the residue dissolved in THF (15 mL). To this cloudy solution was added diisopropylethylamine (0.88 mL, 5.0 mmol) followed by glycine tert-butyl ester (0.30 mL, 2.2 mmol). The reaction was stirred for another 14 h. The volatiles were removed in vacuo at 40° C. The reaction mixture was diluted with ethyl acetate and washed with 1 N aqueous HCl (×2), 10% aqueous Na2CO3 (×2) and brine (×2). The organic phase was dried over anhydrous Na2SO4 and concentrated in vacuo to afford {[(R)-7-(3,5-dichloro-phenyl)-5-methyl-6-oxo-5-(4-trifluoromethoxy-benzyl)-6,7-dihydro-5H-imidazo[1,2-a]imidazole-3-carbonyl]-amino}-acetic acid tert-butyl ester (0.483 g) as a colorless foam.

Provenance & Evidence