A mixture of 1-benzyl-1,2,3,4-tetrahydroquinolin-7-ol (550 mg, 2.30 mM) and triethylamine (0.4 mL) in dry dichloromethane (DCM, 10 mL) was stirred for half an hour under nitrogen atmosphere at room temperature (35° C.). To the stirred reaction mixture, o-tolyl isocyanate (428 mg/ml, 3.45 mM) was added at once and then the reaction mixture was further stirred for 72 hours under N2 atmosphere at RT. The reaction mixture was concentrated under vacuum and then was added distilled water (15 mL) followed by the extraction with ether (3×15 mL). The ether layer was dried over sodium sulphate and concentrated under vacuum to afford the crude product, which was finally chromatographed using chloroform-hexane (1:9) to give 8a as colorless oil. Yield: 700 mg, 81.78%.
