Zinc-catalyzed cycloisomerizations. Synthesis of substituted furans and furopyrimidine nucleosides

Adam Sniady, Audrey Durham, Marco S. Morreale, Andrzej Marcinek, Slawomir Szafert, Tadeusz Lis, Krystyna R. Brzezinska, Takanori Iwasaki, Takashi Ohshima, Kazushi Mashima, Roman Dembinski

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Abstract

(Chemical Equation Presented) 5-Endo-dig cycloisomerization of 1,4- and 1,2,4- mostly aryl-substituted but-3-yn-1-ones in the presence of a catalytic amount of zinc chloride etherate (10 mol %) in dichloromethane at room temperature gave 2,5-di- and 2,3,5-trisubstituted furans in high yields (85-97%). DSC studies confirmed that a solely thermal process does not take place. A relevant catalytic process, employing μ-oxo-tetranuclear zinc cluster Zn4(OCOCF3)6O, yielded bicyclic furopyrimidine nucleosides, when starting from acetyl-protected 5-alkynyl-2′-deoxyuridines (85-86%). Furopyrimidine was deprotected or simultaneously converted into pyrrolopyrimidine nucleoside. The time/concentration dependence for the reaction of 1-phenyl-4-(4-methylphenyl) butynone to 2-(4-methylphenyl)-5-phenylfuran displayed first-order kinetics with the rate dependent on catalyst concentration. The plot of In K0bS versus In[ZnCl2 indicated first-order cycloi-somerization, as referred to ZnCl2 concentration, using both NMR and UV-vis reaction monitoring. The crystal structure of propyl furopyrimidine nucleoside (orthorhombic, P212121, a/b/c = 5.684(2)/6.682(2)/36.02(2) Å, Z = 4) shows C2′-endo deoxyribose puckering, and the base is found in the anti position in crystalline form.

Original languageEnglish
Pages (from-to)5881-5889
Number of pages9
JournalJournal of Organic Chemistry
Volume73
Issue number15
DOIs
Publication statusPublished - Aug 1 2008

All Science Journal Classification (ASJC) codes

  • Organic Chemistry

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    Sniady, A., Durham, A., Morreale, M. S., Marcinek, A., Szafert, S., Lis, T., Brzezinska, K. R., Iwasaki, T., Ohshima, T., Mashima, K., & Dembinski, R. (2008). Zinc-catalyzed cycloisomerizations. Synthesis of substituted furans and furopyrimidine nucleosides. Journal of Organic Chemistry, 73(15), 5881-5889. https://doi.org/10.1021/jo8007995