反应详情

Benzyl bromide (0.233 mol, 27.7 mL) was added to a solution of NaI (0.097 mol, 14.5 g) in acetone (1 L). Natural product UK-2A (1) (0.194 mol, 100 g) was added followed by powdered K2CO3 (0.388 mol, 53 g) and the mixture stirred vigorously overnight. The mixture was diluted with CH2Cl2 (500 mL) and washed with H2O (2×500 mL). The organic layer was dried (MgSO4), and concentrated in vacuo. Recrystallization (EtOAc/hexane) gave 95.5 g (79%) of 2 as an off-white solid (m.p. 169-170° C.) which contained ˜6.5% N-benzylated product (LC-MS). 1H-NMR and MS (M+1 605) were consistent for the title compound (2). The compound was used in the next step without further purification. The N-benzylated by-product could be removed from the mixture prior to recrystallization by filtration of the crude reside through a plug of silica gel (30% acetone/hexane as the eluent).

1. washwashed with H2O (2×500 mL)
2. dry with materialThe organic layer was dried (MgSO4)
3. concentrationconcentrated in vacuo
4. customRecrystallization (EtOAc/hexane)