作者:Karsten Krohn、Ishtiaq Ahmed、Markus John
DOI:10.1055/s-0028-1083361
日期:——
The synthesis of four flavan-3-ols with different substitution patterns and electron densities has been achieved in high stereo- and regioselectivity by a one-step Mitsunobu reaction from the corresponding diols, which were prepared by enantioselective Sharpless dihydroxylation of suitable olefins. The six-membered flavan-3-ols were the only cyclization products and the theoretically possible formation of five-membered rings during the Mitsunobu cyclization was not observed. The flavanols are important starting materials for the synthesis of dimers such as the procyanidins or other coupling products such as the flavan part of the potent DNA polymerase β inhibitor myristinin A. The enantioselectivities of both the Sharpless dihydroxylation and the Mitsunobu cyclization steps were monitored by chiral HPLC.
通过从相应的二醇进行一步Mitsunobu反应,以高立体选择性和区位选择性成功合成了四种具有不同取代模式和电子密度的黄酮-3-醇,这些二醇是通过对合适的烯烃进行手性选择性的Sharpless二羟基化制备的。在Mitsunobu环化过程中,六元环的黄酮-3-醇是唯一的环化产物,理论上可能形成的五元环并未被观察到。这些黄酮醇是合成二聚体(如原花青素)或其他偶联产物(如强效DNA聚合酶β抑制剂myristinin A中的黄酮部分)的重要起始材料。Sharpless二羟基化和Mitsunobu环化步骤的对映选择性通过手性高效液相色谱法进行了监测。