p-Toluenesulfonic acid → 2-amino-4-hydroxy-1,2-dihydrobenzo[f]quinolin-3(4H)-one

Participants

Reaction Conditions

Reaction Steps

Benzyl[4-(benzyloxy)-3-oxo-1,2,3,4-tetrahydrobenzo[t]quinolin-2-yl]carbamate (54, prepared from 2-amino-3-(1-naphthyl)propanoic acid according to the general procedure for synthesis of tert-butyl (3S,4S)-1-(benzyloxy)-4-methyl-2-oxo-1,2,3,4-tetrahydroquinolin-3-ylcarbamate (33) in Example 7) (35 mg, 0.077 mmol) was dissolved in a solution of boron trichloride in DCM (1.0 M, 5.00 mL, 5.00 mmol), and the reaction was heated at 50° C. for 1 h. After being quenched with MeOH (10 mL), the reaction was stirred for 15 min, then treated with silica gel impregnated with p-toluenesulfonic acid (0.68 mEq/g, 2 g, 1.36 mmol). After 1.5 hours, the silica was filtered off and rinsed with MeOH; the silica was then slurried with a 2N solution of ammonia in MeOH for 20 minutes, and filtered. The solids were rinsed with MeOH and the combined filtrates were concentrated in vacuo to afford a solid, which was triturated with Et2O to provide the product as a solid (2 mg, 10%). LCMS m/z 229.0 (M+1). 1H NMR (400 MHz, CD3OD) δ 3.07 (dd, J=15, 15 Hz, 1H), 3.82 (dd, J=16, 6.5 Hz, 1H), 4.00 (dd, J=14, 6 Hz, 1H), 7.45 (dd, J=7, 7 Hz, 1H), 7.58 (dd, J=8, 8 Hz, 1H), 7.67 (d, J=9 Hz, 1H), 7.88 (m, 2H), 8.01 (d, J=9 Hz, 1H).

Provenance & Evidence