Ring-opening of isoxazolidine system: Homologation of 3-aryl into 3-styryl nitrones via intermediate 5-hydroxy-isoxazolidines.
摘要:
High yield conversion of 3-aryl-5-ethoxy-isoxazolidines into 3-styryl nitrones has been achieved by 1,5 h refluxing in aq. H2SO4 or catalytic p-toluensulfonic acid/ethanol media. The rearrangement pathway is interpretable on the basis of the ring-opening process of intermediate 5-hydroxy-isoxazolidines. Formation of a masked 5-OH function has been also developed by basic or acid treatment of 5-acetoxy-isoxazolidines.
Visible-Light-Promoted Synthesis of Vinyloxaziridines from Conjugated Carbonyls
作者:Gustavo Moura-Letts、Brooke E. Austin、Ryan P. Palner、Elissa M. Tobias、Rufai Madiu、Erin L. Doran、Jenna M. Doran、Amari M. Howard、James L. Stroud、Morgan E. Rossi、Dylan A. Moskovitz、Dominic A. Rivera、Michael D. Mullen、Amy H. Zinsky、Rose A. Rosario
DOI:10.1055/a-2153-6687
日期:2024.2
We report the first visible-light-promoted synthesis of vinyloxaziridines from simple conjugated nitrones. We have found that vinyl nitrones formed by the condensation reaction between conjugated carbonyls and hydroxylamines undergo visible-light-promoted energy-transfer isomerization to the respective vinyloxaziridines in very high yields and selectivities. The reaction scope expands to a large array
High yield conversion of 3-aryl-5-ethoxy-isoxazolidines into 3-styryl nitrones has been achieved by 1,5 h refluxing in aq. H2SO4 or catalytic p-toluensulfonic acid/ethanol media. The rearrangement pathway is interpretable on the basis of the ring-opening process of intermediate 5-hydroxy-isoxazolidines. Formation of a masked 5-OH function has been also developed by basic or acid treatment of 5-acetoxy-isoxazolidines.
Synthesis of <i>syn</i>-1,3-Aminoalcohols via a Ru-Catalyzed <i>N</i>-Demethylative Rearrangement of Isoxazolidines and Its Application in a Three-Step Total Synthesis of HPA-12
作者:Chuan-Zhi Yao、Zu-Feng Xiao、Xiao-Shan Ning、Jie Liu、Xiao-Wei Zhang、Yan-Biao Kang
DOI:10.1021/ol502956j
日期:2014.11.7
A highly efficient ruthenium-catalyzed stereospecific N-demethylative rearrangement of isoxazolidines to synthetically useful N–H-1,3-oxazinanes is described. 1,3-Oxazinanes are useful building blocks, which can be further converted to N–H-1,3-aminoalcohols in one step. This new method was used in a three-step gram-scale totalsynthesis of HPA-12 in an overall 24% yield.