Diisopropylethylamine → trans-7-Methoxy-1,2,3,4,4a,5,6,10b-octahydrobenzo[f]quinoline

Participants

Reaction Steps

cis-7-Methoxy-1,2,3,4,4a5,6,10b-octahydrobenzo[f]quinoline 1-Chloroethylchloroformate (4.62 ml, 42.8 mmol) was added with stirring to an ice cooled solution of cis-and trans-7-methoxy-4-methyl-1,2,3,4,4a,5,6,10b-octahydrobenzo[f]quinoline (4.3 g, 18.6 mmol) in dichloromethane (140 ml). The mixture was allowed to warm to room temperature and stirred for a further 2 h. Diisopropylethylamine (4.9 ml, 28 mmol) was added and the mixture heated at reflux for 1 h. The mixture was cooled and concentrated in vacuo before dissolving in methanol (100 ml) and refluxing for 1 h. After cooling, the solvent was removed and the residue partitioned between saturated aqueous K2CO3 (50 ml) and dichloromethane (3×50 ml). The combined organic extracts were washed with brine (50 ml), dried (Na2SO4) and the solvent evaporated to afford a yellow oil. Chromatography on silica using 10% methanol-dichloromethane and 6.6 ml/L 0.880 ammonia as eluent gave trans 7-methoxy-1,2,3,4,4a,5,6,10b-octahydrobenzo[f]quinoline (0.6 g, 30%) as the first eluting isomer.

Provenance & Evidence