Monomeric Dihydroanthraquinones: A Chemoenzymatic Approach and its (Bio)synthetic Implications for Bisanthraquinones
作者:Nirmal Saha、Amit Mondal、Karina Witte、Shailesh Kumar Singh、Michael Müller、Syed Masood Husain
DOI:10.1002/chem.201705998
日期:2018.1.26
by a biomimetic and chemoenzymatic approach using NADPH‐dependent polyhydroxyanthracence reductase (PHAR) from Cochliobolus lunatus followed by Pb(OAc)4 oxidation is reported. Subsequent dimerization through a hetero‐Diels–Alder reaction of the dihydroemodin and dihydrolunatin resulted in (−)‐flavoskyrin (68 %) and (−)‐lunaskyrin (62 %), respectively. Pyridine treatment of (−)‐flavoskyrin and (−)‐lunaskyrin
修饰的双蒽醌是具有笼状结构基序的复杂的二聚体天然产物。对于其生物合成,单体二氢蒽醌已被提议作为关键中间体,尽管还没有从天然来源中分离出来或迄今仍未合成。在这里,通过仿生和化学酶学方法,使用Cochliobolus lunatus的NADPH依赖的多羟基蒽还原酶(PHAR),然后用Pb(OAc)4进行仿生和化学酶学方法合成的二氢大黄素以及二氢大黄素的分离和表征据报道氧化。随后通过二氢大黄素和二氢伦丁的异狄尔斯-阿尔德反应进行二聚,分别导致(-)-黄酮丁草酯(68%)和(-)-氟那斯基林(62%)。吡啶处理(−)‐ flavoskyrin和(−)‐ lunaskyrin的处理使(−)‐ rugulosin和(−)‐ 2,2'- Epi- cytoskyrinrin A的级联反应分别产生64%和60%二聚体中间体。讨论了所描述的合成对通过酶促和自发步骤的组合生物合成双蒽醌的影响。