[C:1]([C:4]1[CH:5]=[C:6]([CH:13]=[CH:14][CH:15]=1)[C:7]([N:10]=C=O)([CH3:9])[CH3:8])(=[O:3])[CH3:2]>Cl>[C:1]([C:4]1[CH:5]=[C:6]([CH:13]=[CH:14][CH:15]=1)[C:7]([NH2:10])([CH3:9])[CH3:8])(=[O:3])[CH3:2]3-Acetyl-α, α-dimethylbenzyl isocyanate 3 (1000 mg, 4.92 mmol) in 8N HCl (30 mL) were refluxed for 30 min. The reaction mixture was cooled to 0° C. and then washed with diethyl ether. The aqueous portion was neutralized with a 10% NaOH solution and extracted with diethyl ether (3×20 mL). The combined organic layers were washed with brine, dried over anhydrous MgSO4, filtered and concentrated. The residue was purified by chromatography eluting with methanol/chloroform to give 24 as a yellow oil (478 mg, 55%). 1H NMR (CDCl3, 400 MHz) δ 1.57 (s, 6H), 2.61 (s, 3H), 3.72 (s, 2H), 7.43 (t, J=7.6 Hz, 1H), 7.75 (d, J=7.6 Hz, 1H), 7.82 (d, J=7.6 Hz, 1H), 8.14 (s, 1H).
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