Water → HCID 57767004, compound

Participants

Reaction Steps

Tetrazole (2.0 equiv., 5.37 mmol, 0.38 g) and di-(tert-butyl) diethylphosphoramidite (1.6 equiv., 4.30 mmol, 1.07 g) were added to a solution of 10 (1.0 equiv., 2.69 mmol, 1.00 g) in anhydrous acetonitrile under Ar atmosphere. The reaction mixture was stirred at room temperature for 1 h. A 70% tert-butyl hydroperoxide solution in water (5.0 equiv., 13.45 mmol, 1.73 g) was added slowly and stirring was continued for 1 h. The reaction mixture was filtered through a glass filter and the filtrate was evaporated under reduced pressure. Purification by column chromatography (dichloromethane/methanol 97.2:2.5) afforded phosphoric acid di-tert-butyl ester 6-(4-nitrophenyl)-5-oxo-5,6-dihydro-pyrido[2′,1′:2,3]imidazo[4,5-c]isoquinolin-9-yl ester (I21). A suspension of I21 in a 4 M HCl solution in isopropanol was stirred at room temperature overnight. The solvent was removed under reduced pressure to give phosphoric acid 5,6-dihydro-6-(4-nitrophenyl)-5-oxo-pyrido[2′,1′:2,3]imidazo[4,5-c]isoquinolin-9-yl ester (76) as a hydrochloride salt (0.47 g, yield=36%, purity (LC)>95%).

Provenance & Evidence