Triphenylphosphine → 1-(2,2-Dimethyl-4-oxotetralin-1-yl)-5-imidazolecarboxylic acid methyl ester

Participants

Reaction Conditions

Reaction Steps

To a solution of 4-hydroxy-3,3-dimethyl-3,4-dihydro-2H-naphthalen-1-one (2.87 g, 13.88 mmol) and methyl 4-imidazolecarboxylate (CAS#17325-26-7, 1.25 g, 9.72 mmol) in THF (80 mL) at 0° C. is added triphenylphosphine (3.68 g, 13.88 mmol) and dimethyl azodicarboxylate (40% in toluene, 5.14 mL, 13.88 mmol) and the cooling bath is removed. After 15 hours, the mixture is concentrated and the resulting residue is dissolved in ethyl acetate (250 mL) and is extracted five times with 1M aqueous HCl (40 mL portions). The acidic aqueous phases are cooled to 0° C. and the pH is adjusted to ca. 12 with 4M aqueous NaOH at 0° C. The aqueous phase is then extracted three times with dichloromethane. The combined organic layers are dried over MgSO4 and filtered, and concentrated. The resulting residue is purified by silica gel flash chromatography (dichloromethane-methanol, 49:1) to give 3-(2,2-dimethyl-4-oxo-1,2,3,4-tetrahydro-naphthalen-1-yl)-3H-imidazole-4-carboxylic acid methyl ester; MS: (ESI) m/z 299.0 (M+H)+; 1H NMR (400 MHz, CDCl3) δ ppm 0.97 (s, 3 H), 1.15 (s, 3 H), 2.63 (d, J=16.8 Hz, 1 H), 2.74 (d, J=16.8 Hz, 1 H), 3.93 (s, 3 H), 6.79 (s, 1 H), 7.02 (d, J=7.6 Hz, 1 H), 7.35 (s, 1 H), 7.47 (t, J=7.6 Hz, 1 H), 7.55 (td, J=7.6, 1.5 Hz, 1 H), 7.86 (s, 1 H), 8.13 (dd, J=7.6, 1.5 Hz, 1 H);

Provenance & Evidence