Bioinspired Diastereoconvergent Synthesis of the Tricyclic Core of Palodesangrens via Diels–Alder Reaction, LiAlH<sub>4</sub>-Mediated Isomerization, and Acid-Mediated Cyclization
作者:Poramate Songthammawat、Sirilak Wangngae、Koki Matsumoto、Chuthamat Duangkamol、Somsak Ruchirawat、Poonsakdi Ploypradith
DOI:10.1021/acs.joc.8b00668
日期:2018.5.4
electron-deficient chalcones as the dienophile. During the reduction of ketone to the corresponding alcohol by LiAlH4, the mixture of endo and exo isomers underwent a novel diastereoconvergent LiAlH4-mediated isomerization to install the desired stereochemistry at C10a. Subsequent pyran ring closure under acidic conditions installed the stereochemistry at the remaining C6. Overall, the tricyclic core of palodesangrens
的环己烯部分的三环6,7-二芳基四氢-6- ħ -苯并[ c ^ ] palodesangrens的色烯核心可在仿生和步骤-经济的方式由所述富电子(之间的Diels-Alder反应来组装ë) -1,3-丁二烯芳烃为二烯,缺电子查耳酮为亲二烯体。在LiAlH 4将酮还原为相应的醇的过程中,内和外异构体的混合物经历了一种新的非对映收敛的LiAlH 4。-介导的异构化以在C10a处安装所需的立体化学。随后在酸性条件下的吡喃环闭合将立体化学安装在剩余的C6上。总体而言,可以分三步制备palodesangrens的三环核,产率最高可达38%。