Direct Synthesis of α-Iodoenones by IPy<sub>2</sub>BF<sub>4</sub>-Promoted Rearrangement of Propargylic Esters
作者:Tatiana Suárez-Rodríguez、Ángel L. Suárez-Sobrino、Alfredo Ballesteros
DOI:10.1021/acs.joc.8b01746
日期:2018.10.19
A direct access to α-iodoeones from iodonium ion and propargylic tosylates or acetates is described. Bis(pyridine) iodonium tetrafluoroborate (IPy2BF4, Barluenga’s reagent) promotes the rearrangement of these propargylic alcohol derivatives in mild conditions. The transformation gives β-unsubstituted, β-monosubstituted, and β,β-disubstituted α-iodoenones in high yields. β-Substituted α-iodoenones are
Catalyst-Free Halogenation of α-Diazocarbonyl Compounds with <i>N</i>-Halosuccinimides: Synthesis of 3-Halooxindoles or Vinyl Halides
作者:Chaoqun Ma、Dong Xing、Wenhao Hu
DOI:10.1021/acs.orglett.6b01346
日期:2016.7.1
A novel catalyst-free halogenative cyclization of N-aryl diazoamides with N-halosuccinimides (NXS) is reported for the synthesis of 3-halooxindoles through a carbene-free mechanism. N-Aryl diazoamides reacted with NXS under mild and catalyst-free conditions to afford the corresponding 3-halooxindoles in good yields. This transformation is proposed to proceed through diazonium ion formation followed
Stereoselective Synthesis of Stannyl Enones via Palladium-Catalyzed and Free Radical Hydrostannation of Alkynyl Ketones with Trineophyltin Hydride
作者:Verónica I. Dodero、Liliana C. Koll、M. Belén Faraoni、Terence N. Mitchell、Julio C. Podestá
DOI:10.1021/jo035396m
日期:2003.12.1
A study on the addition of trineophyltin hydride (1) to alkynones under free radical (AIBN and Et3B) and palladium-catalyzed [(PPh3)(2)PdCl2] conditions is reported. The results obtained indicate that the addition of 1 to eight ynones catalyzed by bis(triphenylphosphine)palladium(II) chloride led in all cases to addition products in very high yields (80-96%). These additions take place with excellent regio- and stereochemistry, leading to the alpha adducts as major products in seven out of the eight cases studied. Also the E adducts, resulting from a syn attack, were the only (seven cases) or the predominant (one case) products. The radical hydrostannations initiated by AIBN of ynones 2-5 with 1 led to addition products in good yields (60-88%); with the more hindered ketones 6 and 7-9 the yields obtained were lower. The radical additions initiated by triethylboron to ynones 2-6 follow a similar pattern but with lower yields; no addition products in the hydrostannation of ynones 7-9 were detected. The new acyl-substituted vinylstannanes, owing to their greater stability compared with that of their tributyl- and trimethylstannyl analogues, can be purified by column chromatography using neutral alumina (in all cases) or silica gel 60 (in most cases) as adsorbents. Full H-1, C-13, and Sn-119 NMR data are given.