A Simplified Synthesis of the Diastereomers of Levuglandin E<sub>2</sub>
作者:Venkataraman Amarnath、Kalyani Amarnath、Tina Masterson、Sean Davies、L. Jackson Roberts
DOI:10.1081/scc-200048945
日期:2005.1.1
report a synthesis of Levuglandin E2, as a mixture of easily separable diastereomers (15‐E2‐isoketals). The key feature is the protection of its reactive aldehyde as dimethyl acetal, which is introduced with 2,2‐dimethoxyethanal and removed in minutes with Montmorillonite K‐10. The synthesis could be modified to the preparation of 15‐E2‐isoketals with stable isotopes or with radiolabels.
Factors determining the course of reaction (i.e., usual coupling vs. abnormal cine -substitution) in the Stille coupling of trisubstituted iodoalkene and trans -vinylstannane were investigated. The palladium-catalyzed reaction with triphenylarsine and lithium chloride in N -methylpyrrolidone gave the normal Stille coupling product in good yield and good selectivity, while the use of N , N -diisopropylethylamine
Fully Stereocontrolled Syntheses of 3-Oxacarbacyclin and Carbacyclin by the Conjugate Addition-Azoalkene-Asymmetric Olefination Strategy
作者:Mikhail Kim、Hans-Joachim Gais
DOI:10.1021/jo060551t
日期:2006.6.1
described. The syntheses are based on the conjugate addition-azoalkene-asymmetric olefination strategy. Its key features are (1) the stereoselective establishment of the complete ω-side chain of 2 and 3 through conjugate addition of the enantiopure C13−C20 alkenylcopper derivative 10 to the enantiopure C6−C12 bicyclic azoalkene 9 and (2) the 5E-stereoselective construction of the α-side chain through a Hor
Aryl- and Alkenyllithium Preparations and Copper-Catalyzed Reaction between the Derived Magnesium Reagents and the Monoacetate of 4-Cyclopentene-1,3-diol
作者:Kenya Nakata、Yuichi Kobayashi
DOI:10.1021/ol0501065
日期:2005.3.1
[reaction: see text] Aryl- and alkenyllithiums, prepared by halogen-lithium exchange with lithium, exchange with n-(or t-)BuLi, stannane-lithium exchange with n-BuLi, and direct lithiation with n-BuLi, were transformed into magnesium reagents with MgCl2 and subjected to CuCN-catalyzed reaction with the title monoacetate. Except for the halogen-lithium exchange with n-BuLi, the other preparations of
Total Synthesis Confirms the Molecular Structure Proposed for Oxidized Levuglandin D<sub>2</sub>
作者:Yu-Shiuan Cheng、Wenyuan Yu、Yunfeng Xu、Robert G. Salomon
DOI:10.1021/acs.jnatprod.6b01048
日期:2017.2.24
because it must be outstandingly efficient to prevail over adduction with proteins and because it requires a unique dehydrogenation. We now report a concise total synthesis that confirms the molecularstructure proposed for ox-LGD2. The synthesis also produces ox-LGE2, which readily undergoes allylic rearrangement to Δ6-ox-LGE2.