New approaches toward the synthesis of (D-homo) steroid skeletons using Mukaiyama reactions
作者:Florence C.E. Sarabèr、Alexander Baranovsky、Ben J.M. Jansen、Maarten A. Posthumus、Aede de Groot
DOI:10.1016/j.tet.2005.11.056
日期:2006.2
Mukaiyama reaction between the silylenolether of 6-methoxytetralone and 2-methyl-2-cyclopentenone or carvone, with transfer of the silylgroup to the receiving enone, gave a second silylenolether. Addition of a carbocation, generated under Lewis acid conditions from 3-methoxy-2-butenol, 3-ethoxy-3-phenyl-2-propenol or 3-methoxy-2-propenol to this second silylenolether gave adducts, which could not
Total Synthesis of Guanacastepene A: A Route to Enantiomeric Control
作者:Mihirbaran Mandal、Heedong Yun、Gregory B. Dudley、Songnian Lin、Derek S. Tan、Samuel J. Danishefsky
DOI:10.1021/jo051470k
日期:2005.12.1
ketone (see compound 41). Actually, cyclization was best accomplished when the terminal double bond of 41 was first converted to an epoxide. Further issues related to the stereochemistry at C5 and, rather surprisingly, the propensity for β-face acetoxylation at C13. Crystallographic verification of the assigned β-stereochemistry at C13 is provided. Finally, a route to opticallyactive material is provided
sulfated diterpenoid glucoside with a unique 5/6/3/6 tetracyclic skeleton with a highly substituted cyclopropane ring deeply embedded into the structure. Herein, we report the first totalsynthesis of this natural product in a concise, efficient, scalable, and highly diastereoselective fashion. The aglucone peyssonnosol was synthesized in 21% overall yield after 15 steps, featuring a Simmons–Smith cyclopropanation
Assessing Synthetic Strategies: Total Syntheses of (±)-Neodolabellane-Type Diterpenoids
作者:Cory Valente、Michael G. Organ
DOI:10.1002/chem.200801161
日期:2008.9.19
Two strategies, namely a cross-metathesis/ring-closing metathesis and Pd-catalyzed Stille allylation/Nozaki-Hiyama-Kishi coupling, are examined for the preparation of neodolabellane-type diterpenoids 1 and 2. Whereas the first approach possessed synthetic limitations, the latter was successfully employed to provide compounds 1 and 2 in 8.8% (14 steps) and 8% (15 steps) overall yields, respectively
Abstract Efficient access to thermodynamically favoured silyl enol ethers deriving from α,α′-dienolizable ketones was produced via easy-made NEt3HCl-mediated isomerization of a regioisomeric mixture of O-silylated products. † deceased on 7 may 1997 § Present adress: Laboratoire de Synthese Organique, associe au CNRS, Universite du Maine, Avenue Olivier Messiaen, B.P. 9 F-72085 Le Mans (France)
摘要 通过易于制备的 NEt3HCl 介导的 O-硅烷化产物的区域异构混合物的异构化,可以有效地获得源自 α,α'-可二烯醇化酮的热力学有利的甲硅烷基烯醇醚。† 1997 年 5 月 7 日逝世 § 现地址:Laboratoire de Synthese Organique, associe au CNRS, Universite du Maine, Avenue Olivier Messiaen, BP 9 F-72085 Le Mans (France)