Oxalyl chloride (15 ul, 0.14 mmol) at RT was added to a solution of indole-5-carboxylic acid (0.02 g, 0.12 mmol) in THF (1 ml). After stirring at RT for 10 h, the mixture was added THF (1 ml) followed by (+)-3-methoxy-morphinan hydrochloride (0.04 g, 0.12 mmol), then triethylamine (0.1 ml, 0.7 mmol) was added and stirred for 18 h. The reaction mixture was filtered and washed with ethyl acetate. The filtrate was washed with saturated Na2CO3 (5 ml), dried (Na2SO4), filtered and concentrated at reduced pressure to give a crude pale brown oil. The crude product was purified by column chromatographed eluting with (MeOH:CH2Cl2=1:10) to give a pale yellow oil (0.013 g, 28% yield).
