Double bond migration on the 22(17→28)abeo-lupane skeleton was investigated using 28-p-toluenesulfonyloxy-lupane (4) and its 20(29)-ene derivative (7) as starting materials. In the case of 4, the double bond, formed between C-17 and C-28 after elimination of the p-toluenesulfonyloxy group followed by E-ring expansion, migrated to C-13 and C-18 under acidic conditions. In the case of 7, the double bond, formed after the elimination and the E-ring expansion, migrated in response to migration of the other double bond, 20(29)-ene, under acidic conditions. First, 20(29)-ene migrated to 19-ene (9), and then 17(28)-ene migrated to 13(18)-ene to form a conjugated 13 (18), 19-diene (10). Further migration proceeded to give an equilibrium mixture of 17α-H-11, 13(18)-diene (11), 12, 17-diene (12) and 17β-H-11, 13(18)-diene (13) in a ratio of 3 : 3 : 5.
以28-对
甲苯磺酰氧基-卢帕烷(4)及其20(29)-烯衍
生物(7)为起始原料,研究了22(17→28)abeo-卢帕烷骨架上的双键迁移。在4的情况下,在酸性条件下,在消除对
甲苯磺酰氧基基团并随后进行E-环扩张后,在C-17和C-28之间形成的双键迁移到C-13和C-18。在7的情况下,在酸性条件下,在消除和E-环扩张后形成的双键迁移响应于另一个双键20(29)-烯的迁移。首先,20(29)-烯迁移到19-烯(9),然后17(28)-烯迁移到13(18)-烯,形成共轭13(18),19-二烯(10)。进一步的迁移产生了17α-H-11,13(18)-二烯(11),12,17-二烯(12)和17β-H-11,13(18)-二烯(13)的平衡混合物,比例为3:3:5。