反应详情

温度

20 °C

The racemic 3-(N-isopropylamino)-5-methoxychroman (IV; 54 g, 0.224 mol) was mixed with an equimolar amount of (+)-di-1,4-toluoyl-D-tartaric acid (98.6 g, 0.244 mol). The mixture was dissolved in boiling ethanol (170 mL)/acetone (70 mL). The salt started to crystallize in the hot solvent mixture but was not filtered off until the solvent had cooled down to room temperature (20° C). The salt was then recrystallized nine times from ethanol acetone (1:5) to give the pure diastereomeric salt. Yield: 35% (54 g) (99% e.e). MD: 166°-168° C. The free enantiomer as the base (R)-3-(N-isopropylamino)-5-methoxychroman was obtained by the extraction of the salt in ether/KOH (1M). Yield: 32%, 17.5 g,

1. dissolutionThe mixture was dissolved
2. customto crystallize in the hot solvent mixture
3. filtrationwas not filtered off until the solvent
4. customThe salt was then recrystallized nine times from ethanol acetone (1:5)
5. customto give the pure diastereomeric salt
6. custom166°-168° C