反应详情

To a solution of lithium diisopropylamide (LDA), prepared from n-BuLi (64.5 ml, 0.1M) and diisopropylamine (10.1 g, 14 ml, 0.1M) in dry THF (100 ml) was added under N2 at -10° C. 5-methylisoxazole (4.2 g, 4.1 ml, 0.05M). The resultant yellow suspension was stirred (mechanical stirrer) at -10° C. for 1 hr before 1-aza-2-methoxy-1-cyclohexene (5.6 g, 0.05M) was added dropwise. A light yellow precipitate was immediately formed. The mixture was allowed to warm to ambient over a period of 20 hr. MeOH (40 ml) was slowly added and the resulting reddish solution was stirred at ambient for 2 hr. The solvents were evaporated in vacuo, and the residual oil was flash column chromatographed on silica gel (EM-60) with 30% MeOH in CH2Cl2 as the eluent to give the desired free base. The HCl salt was then prepared by adding conc HCl to a solution of the free base in methanol. Recrystallization from MeOH/ether gave the title compound (2.9 g, 29%). TLC (30% MeOH in CH2Cl2); Rf=0.53. IR (KBr), cm-1, 3330, 3180, 3030, 2950.

1. additionwas added under N2 at -10° C
2. additionwas added dropwise
3. customA light yellow precipitate was immediately formed
4. temperatureto warm
5. customThe solvents were evaporated in vacuo
6. customchromatographed on silica gel (EM-60) with 30% MeOH in CH2Cl2 as the eluent
7. customto give the desired free base
8. customRecrystallization from MeOH/ether