Stereoselective Synthesis of (−)-Trachelanthic Acid and (+)-Viridifloric Acid, Necic Acid Components of Pyrrolizidine Alkaloids from a Common Intermediate
作者:Haruki Niwa、Takeshi Ogawa、Kiyoyuki Yamada
DOI:10.1246/bcsj.63.3707
日期:1990.12
(1′S,2S,5R)-2-(t-butyl)-5-(1′-hydroxyethyl)-5-isopropyl-1,3-dioxolan-4-one (6), while reduction of 5 with LiBH(s-Bu)3 in ether gave the (1′R)-isomer 7 predominantly. (−)-Trachelanthic acid (1) and (+)-viridifloric acid (2) were synthesized upon hydrolysis of 6 and 7, respectively.
(2S,5R)-5-乙酰基-2-(叔丁基)-5-异丙基-1,3-dioxolan-4-one (5) 中的侧链酮基的非对映选择性还原 (i-Bu)乙醚中的 2AlH 得到 (1'S,2S,5R)-2-(t-丁基)-5-(1'-羟乙基)-5-异丙基-1,3-dioxolan-4-one (6),同时还原5 与 LiBH(s-Bu)3 在乙醚中主要得到 (1'R)-异构体 7。(-)-草根酸 (1) 和 (+)-绿花酸 (2) 分别在 6 和 7 水解后合成。