Straightforward Enantioselective Synthesis of Both Enantiomers of Karahana Lactone Using a Domino Ring-Closure Sequence
作者:Jean-Marie Galano、Gérard Audran、Honoré Monti
DOI:10.1016/s0040-4020(00)00645-1
日期:2000.9
straightforward enantioselective synthesis of both enantiomers of karahana lactone is described starting from enantiopure (R) or (S)-4-hydroxy-3-methyl-cyclohex-2-en-1-one. The key step of the sequence is an acid-induced domino reaction with three pathways running. Because of the first description of karahana lactone as a solid, the structure was secured by X-ray structuralanalysis.
The first total syntheses of the proposed structures of kopeolin (1) and kopeolone (3) have been achieved from a common enantiopure chiral building block obtained by a chemoenzymatic enantioconvergent methodology. The syntheses feature two key steps: a one‐pot reduction/diastereoselective protonation followed by a highly diastereoselective addition of an organocerate. The synthetic structures were
A ring-closing metathesis approach to the bicyclo[4.3.1]decane core of caryolanes
作者:William P.D. Goldring、Warren T. Paden
DOI:10.1016/j.tetlet.2010.11.138
日期:2011.2
A synthesis of highly substituted and sterically congested bicyclo[4.3.1]decenes, a structure embedded in the core 4,7,6-tricyclic system of natural caryolanes, was successfully achieved via a ring-closing metathesis (RCM) reaction of syn-1,3-diene substituted cyclohexanols. The construction of the diene substrates, starting from 4-acetoxy-3-methyl-2-cyclohexen-1-one, employed diastereoselective copper-mediated
Asymmetric [4+2] cycloadditions employing 1,3-dienes derived from (R)-4-t-butyldimethyl-silyloxy-2-cyclohexen-1-one
作者:Zhengmao Hua、Lei Chen、Yan Mei、Zhendong Jin
DOI:10.1016/j.tetlet.2009.09.055
日期:2009.12
1,3-Dienes derived from (R)-4-t-butyldimethylsilyloxy-2-cyclohexen-1-one react with activated dienophiles to form predominately (or sometimes exclusively) syn/endo products. These controlled [4+2] cycloadditions increase the asymmetric complexity from one asymmetric center in the starting material to five asymmetric centers in the products in a single step, and provide a powerful approach for the asymmetric synthesis of compounds containing the bicyclo[2.2.2]octanone carbon skeleton. (C) 2009 Elsevier Ltd. All rights reserved.
Total Syntheses and Structural Revision of α- and β-Diversonolic Esters and Total Syntheses of Diversonol and Blennolide C