Alternative and Expedient Asymmetric Syntheses of l-(+)-Noviose
摘要:
L-(+)-Noviose, the sugar component of the antibiotic novobiocin, was synthesized from readily available non-carbohydrate starting materials relying on stoichiometric and asymmetric processes by two independent methods, comprising six and nine steps, in 27 and 20% overall yields, respectively.
Enantioselective Total Syntheses of Grayanane Diterpenoids: (−)-Grayanotoxin III, (+)-Principinol E, and (−)-Rhodomollein XX
作者:Lingran Kong、Hang Yu、Mengping Deng、Fanrui Wu、Zhe Jiang、Tuoping Luo
DOI:10.1021/jacs.2c01692
日期:2022.3.30
Enantioselective total syntheses of (−)-grayanotoxin III, (+)-principinol E, and (−)-rhodomollein XX were accomplished based on a convergent strategy. The left- and right-wing fragments were assembled via the diastereoselective Mukaiyama aldol reaction catalyzed by a chiral hydrogen bond donor. The unique 7-endo-trig cyclization based on a bridgehead carbocation forged the 5/7/6/5 tetracyclic skeleton
(-)-grayanotoxin III、(+)-principinol E 和 (-)-rhodomollein XX 的对映选择性全合成是基于收敛策略完成的。通过手性氢键供体催化的非对映选择性 Mukaiyama 羟醛反应组装左翼和右翼片段。基于桥头碳阳离子的独特的 7 - endo -trig 环化形成了 5/7/6/5 四环骨架,该骨架经过氧化还原操作和 1,2-迁移以获取不同的格雷烷二萜类化合物。
Convergent Total Synthesis of Principinol D, a Rearranged Kaurane Diterpenoid
作者:Aneta Turlik、Yifeng Chen、Anthony C. Scruse、Timothy R. Newhouse
DOI:10.1021/jacs.9b03751
日期:2019.5.22
convergent fragment coupling approach, wherein the central seven-membered ring is synthesized at a latestage. The bicyclo[3.2.1]octane fragment is accessed by a Ni-catalyzed α-vinylation reaction. Strategic reductions include a diastereoselective SmI2-mediated ketone reduction with PhSH and a new protocol for selective ester reduction in the presence of ketones. The convergent strategy reported herein may be
报道了一种重排的贝壳杉烷二萜类普林匹诺 D 的全合成。这种grayanane天然产物是通过会聚片段耦合方法构建的,其中中央七元环是在后期合成的。双环[3.2.1]辛烷片段通过Ni催化的α-乙烯基化反应获得。战略性减少包括使用 PhSH 进行非对映选择性 SmI2 介导的酮还原,以及在酮存在下进行选择性酯还原的新方案。本文报道的收敛策略可能是进入更大类别的贝壳杉二萜类化合物的切入点。
Conversion of Torgov's Synthesis of Estrone into a Highly Enantioselective and Efficient Process
作者:Yeung、Rong-Jie Chein、E. J. Corey
DOI:10.1021/ja0742434
日期:2007.8.1
A very direct and efficient conversion of the achiral Torgov diketone into the natural form of O-methyl estrone is described.
Highly enantioselective reduction of 1,3-cyclopentanediones was conducted using an oxazaborolidine derived from L-threonine and a borane complex to give either 1,3-cyclopentanediols or 3-hydroxycyclopentanones in high enantiomeric purity by choosing appropriate reduction conditions. (C) 2000 Elsevier Science Ltd. All rights reserved.