- Syntheses of Denudatine Diterpenoid Alkaloids: Cochlearenine, N-Ethyl-1α-hydroxy-17-veratroyldictyzine, and Paniculamine
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The denudatine-type diterpenoid alkaloids cochlearenine, N-ethyl-1α-hydroxy-17-veratroyldictyzine, and paniculamine have been synthesized for the first time (25, 26, and 26 steps from 16, respectively). These syntheses take advantage of a common intermediate (8) that we have previously employed in preparing aconitine-type natural products. The syntheses reported herein complete the realization of a unified strategy for the preparation of C20, C19, and C18 diterpenoid alkaloids.
- Kou, Kevin G. M.,Li, Beryl X.,Lee, Jack C.,Gallego, Gary M.,Lebold, Terry P.,Dipasquale, Antonio G.,Sarpong, Richmond
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- A unifying synthesis approach to the C18-, C19-, and C20-diterpenoid alkaloids
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The secondary metabolites that comprise the diterpenoid alkaloids are categorized into C18, C19, and C20 families depending on the number of contiguous carbon atoms that constitute their central framework. Herein, we detail our efforts to prepare these molecules by chemical synthesis, including a photochemical approach, and ultimately a bioinspired strategy that has resulted in the development of a unifying synthesis of one C18 (weisaconitine D), one C19 (liljestrandinine), and three C20 (cochlearenine, paniculamine, and N-ethyl-1α-hydroxy-17-veratroyldictyzine) natural products from a common intermediate.
- Kou, Kevin G. M.,Kulyk, Svitlana,Marth, Christopher J.,Lee, Jack C.,Doering, Nicolle A.,Li, Beryl X.,Gallego, Gary M.,Lebold, Terry P.,Sarpong, Richmond
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supporting information
p. 13882 - 13896
(2017/11/06)
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- Iridium complex-catalyzed reaction of 1,6-enynes: Cycloaddition and cycloisomerization
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(Chemical Equation Presented) 1,6-Enynes reacted with monoynes to give cyclohexadiene derivatives in the presence of a catalytic amount of [lr(cod)Cl]2/ligand. DPPE was most suitable for cycloaddition. Diastereoselective cycloaddition was also possible. In the absence of monoynes, 1,6-enynes cycloisomerized to (Z)-1-alkylidene-2-methylenecyclopentane derivatives. DPPF was most suitable for cycloisomerization. These results are the first examples of highly Z-selective cycloisomerization.
- Kezuka, Satoko,Okado, Toshiaki,Niou, Eri,Takeuchi, Ryo
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p. 1711 - 1714
(2007/10/03)
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- Iridium complex-catalyzed highly selective cross [2 + 2 + 2] cycloaddition of two different monoynes: 2:1 Coupling versus 1:2 coupling
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(Matrix presented) Highly selective cross [2 + 2 + 2] cycloaddition of two different monoynes is achieved by using a catalytic amount of [Ir(cod)Cl] 2 and ligand. The ligand had a considerable effect on the reaction. When 1,2-bis(diphenylphosph
- Takeuchi, Ryo,Nakaya, Yoshihiko
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p. 3659 - 3662
(2007/10/03)
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- The synthesis and Diels-Alder reactions of (E)- and (Z)-1-methoxy-3-(phenylsulfinyl)buta-1,3-dienes
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The mild and efficient generation of benzenesulfenic acid by the thermolysis of ethyl 2-ethoxycarbonyl-3-(phenylsulfmyl)butanoate 8 in refluxing dichloromethane, and its in situ trapping with (E)- and (Z)-1-methoxybut-2-en-3-yne to form (E)-1-methoxy-3-(p
- Adams, Harry,Anderson, James C.,Bell, Richard,Jones, D. Neville,Peel, Michael R.,Tomkinson, Nicholas C. O.
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p. 3967 - 3973
(2007/10/03)
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- Cyclotrimerisation catalytique d'alcynes par des complexes du nickel formes ''in situ''
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Catalytic cyclotrimerization of acetylenic compounds by transient complexes formed in the reduction of nickel halides by magnesium, occurs with many alkynes; however, this cyclization is hindered when bulky groups are close neighbors of the triple bond or when acceptor groups are in the α position with respect to the unsaturated carbon.On the other hand, the yield of trimer increases to become quantitative with releasing substituents.
- Alphonse, P.,Moyen, F.,Mazerolles, P.
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p. 209 - 216
(2007/10/02)
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- Elimination and Addition Reactions. Part 38. Synthesis and Reactivity of Dieine-bis-sulphonium Salts
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Buta-1,3-diene-1,4-bis-sulphonium salts have been synthesised from buta-1,3-diyne.Reactions with oxygen, sulphur, nitrogen, and carbon nucleophiles have been examined.Except for primary amines and anions of enolisable carbon acids, 1,4-addition and subsequent elimination of the sulphonium group is observed in all cases.Subsequent addition occurs with alkoxide and thiolate ions, and is followed by dealkylation of the remaining sulphonium group or its displacement by allylic substitution.When hydroxy-thiols or dithiols are used, a second intramolecular addition at carbon 4 yields cyclic products.Such products are not formed from hydroxy-amines.The mono-adducts formed from alkenyl-thiols are potentially capable of, but do not undergo, intramolecular Diels-Alder reactions under a variety of conditions.Neither are intramolecular reactions found in the adduct with 2-methoxycarbonylethanethiol or in the bis-adduct formed by subsequent additions of azide ion and propene-3-thiolate ion.
- Duggan, Peter J.,Leng, John L.,Marshall, Donald R.,Stirling, Charles J. M.
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p. 933 - 939
(2007/10/02)
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