Preparation of 1,2,5-Trisubstituted 1<i>H</i>-Imidazoles from Ketenimines and Propargylic Amines by Silver-Catalyzed or Iodine-Promoted Electrophilic Cyclization Reaction of Alkynes
作者:Xiaorong Zhou、Zheng Jiang、Lexing Xue、Ping Lu、Yanguang Wang
DOI:10.1002/ejoc.201500704
日期:2015.9
From readily available propargylic amines, 1,2,5-trisubstituted imidazoles are efficiently obtained through a cascade reaction catalyzed by AgOTf or promoted by molecular iodine. The AgOTf-catalyzed reaction involves nucleophilic addition of propargylic amine to ketenimine, a silver-catalyzedelectrophiliccyclizationreaction of alkyne, and a tautomerism/isomerism/metal-H exchange cascade. The iodine-mediated
Synthesis of thiazolo[2,3-<i>b</i>]quinazoline derivatives <i>via</i> base-promoted cascade bicyclization of <i>o</i>-alkenylphenyl isothiocyanates with propargylamines
A highly efficient cascade bicyclization reaction of o-alkenylphenyl isothiocyanates with propargylamines has been developed, which affords a series of thiazolo[2,3-b]quinazolines in good to excellent yields by using K2CO3 as a base in MeCN at 80 °C. This method is transition-metal-free and operationally simple with broad functional group tolerance. Mechanistically, 6-exo-trig hydroamination followed
Atom-Economical Synthesis of 2-Aminoimidazoles via [3+2] Annulation Catalyzed by Titanacarborane Monoamide
作者:Zuowei Xie、Yang Wang、Hao Shen
DOI:10.1055/s-0030-1259713
日期:2011.4
An atom-economical synthesis of 2-aminoimidazoles catalyzed by a titanacarborane monoamide is reported. Reactions of propargylamines with carbodiimides, in the presence of 5 mol% [Ï:η ¹:η 5-(OCH2)(Me2NCH2)C2B9H9]Ti(NMe2), afford a new class of substituted 2-aminoimidazoles via [3+2] annulation in good to excellent yields. A possible reaction mechanism is proposed.