Total Synthesis of an Atropisomer of the
<i>Schisandra</i>
Triterpenoid Schiglautone A
作者:Binjie Ma、Yifan Zhao、Chi He、Hanfeng Ding
DOI:10.1002/anie.201809076
日期:2018.11.19
A diastereoselective approach for the total synthesis of an unusual atropisomer of the Schisandra triterpenoid (±)‐schiglautone A is described. The efficient synthetic strategy features three key transformations: 1) two sequential titanium(III)‐catalyzed radical cyclization/homologation reactions to construct the trans‐fused [6,7] bicycle as well as install the quaternary carbons at C10 and C14 with
Total Synthesis of Meayamycin and <i>O</i>-Acyl Analogues
作者:Christopher Gartshore、Shinji Tadano、Prem B. Chanda、Anindya Sarkar、Naidu S. Chowdari、Sanjeev Gangwar、Qian Zhang、Gregory D. Vite、Jelena Momirov、Dale L. Boger
DOI:10.1021/acs.orglett.0c03308
日期:2020.11.6
short, scalable total synthesis of meayamycin is described by an approach that entails a longest linear sequence of 12 steps (22 steps overall) from commercially available chiral pool materials (ethyl l-lactate, BocNH-Thr-OH, and d-ribose) and introduces the most straightforward preparation of the right-hand subunit detailed to date. The use of the approach in the divergent synthesis of a representative
stereochemistry of the C-5 position was introduced by asymmetric reduction with (R)-BINAl-H. Segment B having a series of stereogeniccenters was synthesized from (R)-malic acid and the stereogeniccenters at the C-8 and C-9 positions were prepared by a combination of Wittig reaction and Sharpless asymmetric dihydroxylation reaction. The conjugated Z,Z,E-triene moiety of fostriecin, corresponding to segment
描述了通过高度收敛的途径全合成抗肿瘤抗生素 fostriecin (CI-920)。本全合成的一个特征是合成是通过三个片段 A、B 和 C 的偶联过程实现的。 与片段 A 相对应的磷叶菌素的不饱和内酯部分是由已知的霍纳-埃蒙斯试剂构建的,并且 C-5 位置的立体化学是通过与 (R)-BINAl-H 的不对称还原引入的。具有一系列立体中心的片段B由(R)-苹果酸合成,C-8和C-9位置的立体中心通过Wittig反应和Sharpless不对称二羟基化反应的组合制备。共轭的 Z,Z,E-三烯基叶酸,对应于 C 段,最终通过Wittig反应和Stille偶联反应构建。已知对抗肿瘤活性至关重要的磷酸酯部分通过两种途径引入:(i) 单羟基衍生物的直接磷酸化,其中其他羟基被甲硅烷基保护;(ii) 环状磷酸酯衍生物的环状磷酸化和选择性裂解。虽然前一种途径与其他组报道的基本相同,但后一种途径较前一种新颖且更
Towards the Total Synthesis of Pamamycin-607: Preparation of the Eastern Part (C8–C18 Fragment)
Pamamycin-607 belongs to a group of homologous macrodiolides, produced by various “Streptomyces”, that possess remarkable autoregulatory antifungal, antibacterial and anion-transfering activities. The synthesis of the non-racemic C8–C18 portion of pamamycin-607 is reported here and involves a route that features a stereoselective aldol condensation followed by a stereocontrolled reductive amination