Au-Catalyzed Synthesis of 5,6-Dihydro-8H-indolizin-7-ones from N-(Pent-2-en-4-ynyl)-β-lactams
摘要:
Au-catalyzed synthesis of 5,6-dihydro-8H-indolizin-7-ones from readily available N-(pent-2-en-4-ynyl)-beta-lactams is developed. In this reaction, a 5-exo-dig cyclization of the beta-lactam nitrogen to the Au-activated C-C triple bond is followed by heterolytic fragmentation of the amide bond, forming a highly nucleophilic acyl cation. An expedient formal synthesis of indolizidine 167B was easily achieved using this new method.
Effect of ester on rhodium-catalyzed intermolecular [5+2] cycloaddition of 3-acyloxy-1,4-enynes and alkynes
作者:Casi M. Schienebeck、Patrick J. Robichaux、Xiaoxun Li、Lianqing Chen、Weiping Tang
DOI:10.1039/c3cc40634b
日期:——
We systematically examined the effect of different esters on the rhodium-catalyzed intermolecular [5+2] cycloaddition of 3-acyloxy-1,4-enynes and alkynes with a concomitant 1,2-acyloxy migration. Significant rate acceleration was observed for benzoate substrates bearing an electron-donating substituent. The cycloaddition can now be conducted under much more practical conditions for most terminal alkynes.
Convergent Synthesis of Fostriecin via Selective Alkene Couplings and Regioselective Asymmetric Dihydroxylation
作者:Omar Robles、Frank E. McDonald
DOI:10.1021/ol902365n
日期:2009.12.3
synthesis of fostriecin is described, featuring sequential palladium-catalyzed Negishi cross couplings to form the C7−C8 bond and C8−methyl bond, followed by late-stage regio- and stereoselective dihydroxylation of C8−C9.
Cohalogenation of alkenes 6 by N-bromosuccinimide (NBS) in 3-methylpent-2-en-4-yn-1-ol provides β-bromo-3-methylpent-2-en-4-ynyl ether 7 precursors of 3-(penta-1,3,4-trienyloxy)cycloalkenes 9 which react chemo-and regio-selectively with NBS in methanol to give bromovinyl acetals10.
Selectivity for Alkynyl or Allenyl Imidamides and Imidates in Copper-Catalyzed Reactions of Terminal 1,3-Diynes and Azides
作者:Sourav Ghorai、Daesung Lee
DOI:10.1021/acs.orglett.0c03861
日期:2021.2.5
Copper-catalyzed reactions of terminal 1,3-diynes with electron-deficient azides to generate either 3-alkynyl or 2,3-dienyl imidamides and imidates are described. The selectivity depends on the diyne substituents and the nucleophile that reacts with the ketenimide intermediate generated from the corresponding triazole precursor. Reactions of 1,3-diynes containing a propargylic acetate afford [3]cumulenyl