Dicyclohexylamine → (r)-2-Bromoisovaleric acid dicyclohexylamine salt
反応式
[Br:1][C@H:2]([CH:6]([CH3:8])[CH3:7])[C:3]([OH:5])=[O:4].[CH:9]1([NH:15][CH:16]2[CH2:21][CH2:20][CH2:19][CH2:18][CH2:17]2)[CH2:14][CH2:13][CH2:12][CH2:11][CH2:10]1>CCCCCC>[CH:16]1([NH:15][CH:9]2[CH2:10][CH2:11][CH2:12][CH2:13][CH2:14]2)[CH2:17][CH2:18][CH2:19][CH2:20][CH2:21]1.[Br:1][C@H:2]([CH:6]([CH3:8])[CH3:7])[C:3]([OH:5])=[O:4]参加物
4
反応条件
- 温度
- 5 °C
実験手順
To 325.2 g of a hexane solution of (R)-2-bromoisovaleric acid obtained in Example 4 (containing 75.0 g of (R)-2-bromoisovaleric acid), 530.9 g of hexane and 269.7 g of2-propanol were further added. Seed crystals were added when about ⅔ for 72.5 g of dicyclohexylamine was added continuously for 1.0 hour under a nitrogen atmosphere at 5° C. to crystallize. Further, after continuously adding the remaining about ⅓ for dicyclohexylamine at 5° C. for 0.5 hours, they were stirred at 5° C. for 1 hour. The obtained crystals were filtered under a reduced pressure and then the crystals were washed for 3 times with 150 ml of hexane. The obtained wet crystals were dried under a reduced pressure to obtain 126.45 g of a (R)-2-bromoisovaleric acid dicyclohexylamine salt (optical purity 98.0% ee, crystallization yield 87%, apparent purity 98.9%, impurity content 2-hydroxy isovaleric acid: not detected, bromine content: 0.64%).