反应详情

To a hot solution of (L)-DBTA (7.2 g, 20 mmol) in MeOH (75 mL) with stirring was added a solution of racemic 3-methyl-1-(pyridin-2-yl)butan-1-amine (3.3 g, 20 mmol) in MeOH (30 mL) dropwise. After addition, the resulting suspension was stirred for 5 min under reflux and cooled in air for about 5 min. The resulting precipitate was collected by vacuum filtration, washed with cold MeOH, air-dried and recrystallized from MeOH (200 mL) to give (L)-DBTA salt of (S)-3-methyl-1-(pyridin-2-yl)butan-1-amine as white solid (1.95 g, 95.6% ee). The ee of the compound was determined by acetylating small samples with acetyl chloride and analyzing the products by chiral HPLC: Daicel Chiralpak AD-H, 90:10 v/v hexanes-IPA (+0.5% Et3N), 1.0 ml min−1, λ=254 nm, Rt=5.8 mins (R), Rt=7.5 min (S).

1. additionAfter addition
2. temperatureunder reflux
3. temperaturecooled in air for about 5 min
4. filtrationThe resulting precipitate was collected by vacuum filtration
5. washwashed with cold MeOH
6. customair-dried
7. customrecrystallized from MeOH (200 mL)