[Br:1][C:2]1[CH:3]=[CH:4][C:5]2[CH:10]([CH2:11][C:12]([OH:14])=[O:13])[O:9][CH2:8][CH2:7][C:6]=2[CH:15]=1.CC1C=CC([C@H](N)C)=CC=1.Cl>C(#N)C.O>[Br:1][C:2]1[CH:3]=[CH:4][C:5]2[C@H:10]([CH2:11][C:12]([OH:14])=[O:13])[O:9][CH2:8][CH2:7][C:6]=2[CH:15]=1To a suspension of 2-(6-bromo-3,4-dihydro-1H-2-benzopyran-1-yl)acetic acid (55 g, 203 mmol) in acetonitrile (375 mL) and water (40 mL) was added a solution of (R)-1-(4-methylphenyl)ethylamine (27.45 g, 203 mmol) in acetonitrile (370 mL). The mixture was heated to reflux and the resulting solution cooled to room temperature. A precipitate appeared upon cooling. After stirring for 2 h the salt was filtered off, washed with 95/5 acetonitrile/water (80 mL), and dried in vacuo. The salt was recrystallized in 95/5 acetonitrile/water to give a solid which was suspended in water (390 mL) and treated with 6N HCl (17 mL). After stirring for 1.5 h, filtration, washing, and drying gave the title compound (98% e.e.) as a white solid.
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