[4+2] Cycloaddition of the highly electrophilic imine 2 to 1,3‐butadiene (1) furnished the Diels‐Alder product 3. Hydrolysis of the geminal diester provided (±)‐Baikiain hydrochloride (4). Cis‐Hydroxylation of the double bond of 3 afforded 8. The trans product 9 was prepared via ring opening of the epoxide 5. The regioselective hydroboration/oxidation of 3 provided 7 which was oxidized to 11. Halolactonization
[4 + 2] 高亲电性
亚胺 2 环加成到
1,3-丁二烯 (1) 提供 Diels-Alder 产物 3。孪生二酯的
水解提供 (±) -Baikiain 盐酸盐 (4)。3 的双键顺式羟基化得到 8。反式产物 9 通过
环氧化物 5 的开环制备。3 的区域选择性
硼氢化反应/氧化得到 7,将其氧化为 11。N-
甲苯磺酰基衍
生物 12 的卤代内酯化
白藜芦醇经官能团转化后得到2-羟甲基-
哌啶-4-ol 15。