反应详情

To a solution of lithium diisopropylamide (LDA), prepared from n-BuLi (125 ml, 0.2M) and diisopropylamine (20.2 g, 28.1 ml, 0.2M) in dry THF (100 ml) was added under N2 at -30° to -10° C., 5-methylisoxazole (8.3 g, 0.1M). The resultant yellow suspension was mechanically stirred at -10° C. for 1 hr before 1-aza-2-methoxy-1-cycloheptene (12.7 g, 0.1M) was added dropwise. After the addition was complete, a yellow solid separated and the mixture was allowed to warm to ambient over a period of 19 hr. Then dry MeOH (50 ml) was slowly added and the resultant reddish solution was vigorously stirred at ambient for 2 hr and filtered through a silica gel pad. The filtrate was 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 amine, which was further recrystallized from MeOH/Et2O to give the title compound (5.75 g, 30%), mp>230° C. TLC (30% MeOH in CH2Cl2): Rf=0.40. IR (KBr) cm-1, 3400-3200 (broad), 1660, 1635.

1. additionwas added under N2 at -30° to -10° C.
2. additionwas added dropwise
3. additionAfter the addition
4. customa yellow solid separated
5. temperatureto warm
6. additionThen dry MeOH (50 ml) was slowly added
7. filtrationfiltered through a silica gel pad
8. customThe filtrate was evaporated in vacuo
9. customchromatographed on silica gel (EM-60) with 30% MeOH in CH2Cl2 as the eluent