金属离子催化转化人参皂苷Rg1生成Rh1

Metal ions catalyzed conversion of ginsenoside Rg1 to Rh1

考察了在不同金属离子和不同溶剂体系催化转化人参皂苷Rg1生成Rh1的情况,结果选择Fe^3+为催化剂,乙二醇-水为反应体系。优化了Fe3+催化转化的反应条件,考察了产物与反应时间的关系,并阐明催化反应的过程。结果表明,在乙二醇-水体系中,Fe^3+催化生成的产物20(S,R)-Rh1最多。在乙二醇体积分数50%、Fe^3+浓度0.8 mol/L、40℃反应16 h条件下,制备的产物得率为71.6%,其中20(S,R)-Rh1的质量分数为64.9%。该催化反应过程是人参皂苷Rg1 C-20位上的葡萄糖苷键在Fe^3+的催化作用下,裂解生成20(S,R)-Rh1,同时发生脱水反应生成Rk3和Rh4,当20(S,R)-Rh1积累到一定量时发生水合反应生成25(S,R)-OH-Rh1。

The conversions of ginsenoside Rg1 to Rh1 catalyzed by different metal ions and solvent systems were investigated. Fe^3+ was chosen as catalyst and ethylene glycol-water as reaction system. The reaction conditions of Fe^3+ catalytic conversion were optimized. The relationship between product and reaction time was investigated and the process of catalytic reaction was clarified. The results showed that the yield of 20(S,R)-Rh1 was the highest produced by Fe^3+ catalysis in the ethylene glycol-water system. Under the conditions of 50% ethylene glycol, 0.8 mol/L Fe^3+ and 16 h reaction time at 40 ℃, the yield of the product was 71.6%, and the content of 20(S,R)-Rh1 was 64.9%. The catalytic reaction process is that the glucoside bond at the C-20 position of ginsenoside Rg1 is cracked to form 20(S,R)-Rh1 catalyzed by Fe^3+, and dehydration reaction occurs to form Rk3 and Rh4. When 20(S,R)-Rh1 accumulates to a certain amount, hydration reaction occurs to form 25(S,R)-OH-Rh1.