【摘要】 异青蒿乙素(A)可用R(+)-香草醛为原料,通过十步合成3(亦能从2降解而得),然后由3经5得到6,最后用二苯二硒脱氢和间氯过苯甲酸环氧化而成.环氧的构型经~1H NMR及双竖键破环反应证明.α-次甲基γ-内酯的构型用圆二色散测定. 结构和内酯构型最后经X射线衍射确证。更多还原

【Abstract】 Isoarteannuin B （4）, the stereoisomer of arteannuin B （1）, was synthesized. The norsesquiterpenoid laetone 3 obtained from 10 R （+）-citronellal was converted into 6 which on exposure to lithium diisopropylamide and subsequent treatment of the enolate with diphenyldiselenide gave the phenylselenide 7. The selenide was oxidized with H₂O₂ to yield α-methylene-γ-lactone 8. Further oxidation of 8 with m-chloroperbenzoic acid gave a mixture of two stereoisomers which was then separated into isoarteannuin B （4） and its stereoisomer 9 by TLC. The epoxy configurations were postulated based on their ¹H NMR spectra in combination with the results of diaxial opening of epoxide on treatment with formic acid. The configuration of α-methylene-γ-laetone was determined by circular dichroism measurement. The structure and configuration of the lactone were ultimately confirmed by X-ray diffraction analysis.更多还原