若干青蒿素和青蒿乙素反应中间体的圆二色谱研究

STUDIES ON CIRCULAR DICHROISM OF SOME REACTIONAL INTERMEDIATES OF ARTEMISININ AND ARTEMISININ B

前文报道了青蒿素反应中间体(1)的4,5位双键会引起α-顺式-γ-内酯的Cotton效应符号的反转。为进一步论证这一点和了解A环中3,4位或4,5位双键对生色团δ-内酯和α,β不饱和γ-内酯的Cotton效应符号是否有影响,应用圆二色谱(CD)对六对在A环中不含双键和含双键的青蒿素和青蒿乙素反应中间体γ-内酯(化合物1～4和7～10),δ-内酯(化合物5～6)和环内α,β不饱和γ-内酯(化合物11～12)的A,B环和B,C环的稠合方式进行了CD的测定。

This paper reports circular dichroism, sector and the olefin octant projection of 6- pair synthetic intermediates of Qinghaosu (artemisinin) and Qinghaosu B (artemisinin B):γ - lactone ( compounds 1～4, 7～10 ), δ - lactone (compounds 5～6 ) and endo -α,β - unsaturated-γ - lactone (compounds 11～ 12 ). The relationship between double bond in the ring A and Cotton effect signs of diffrent lactone chromophore has been studied. By using lactone sector rule, the olefin octant rule, allylic oxygen rule and Beecham rule with C = C - C - O and C = C -C=O chromophore, their absolute configurations were assigned. The results show that the Cotton effect signs of lactone chromophore of compounds 2,4,6, and 12 should be inverted while compounds 8 and 10 are independent on the double bond in ring A.