Elucidation of the stereostructure of the annonaceous acetogenin (+)-montecristin through total synthesis
作者:Christian Harcken、Reinhard Brückner
DOI:10.1039/b002905j
日期:——
Total syntheses of ent-5-epi-montecristin (1a) and of (−)-montecristin (1b) were accomplished. The stereocenters of compounds 1a and 1b were established by asymmetric dihydroxylations of the trans-configurated β,γ-unsaturated esters 6 ( → 4, up to 80% ee; Scheme 3; improved procedure with up to 94% ee: Scheme 7) and 56 ( → 55, 97% ee: Scheme 9) while the stereogenic CC bonds stem from the carbocuprations
完成了ent -5- epi- montecristin(1a)和(-)-montecristin(1b)的总合成。化合物1a和1b的立体中心是通过反式构型的β,γ-不饱和酯6的不对称二羟基化而建立的(→ 4,至多80%ee;方案3;改进的程序,至多94%ee:方案7)和56(→ 55,97%ee的:方案9),而立体ç C键从carbocuprations干48 → 49和50 → 51(方案9)。用PPh 3和DEAD处理羟基内酯27(方案7), 3a(方案12)和3b(方案13),我们发现无外消旋的脱水作用生成丁烯内酯26,无差向异构化的脱水作用生成丁烯内酯2a和2b 。有关的[ α ] d合成的值 1A和1B到[ α ] d天然(+)的值- montecristin,测定其侧链立体中心的绝对构型为[R 。