Refernces
10.1021/jo201113r
The research focuses on the oxidative intramolecular bromo-amination of N-alkenyl sulfonamides and N-alkenoxyl sulfonamides via the umpolung of alkali metal bromides, aiming to develop a method for synthesizing nitrogen-containing heterocycles without the use of toxic heavy metals or organic brominating reagents. The experiments involved screening various bromo reagents and oxidants for the intramolecular bromo-amination, with a particular emphasis on using KBr as the bromo reagent and Oxone as the oxidant in acetonitrile (MeCN) as the optimal conditions. The reactants included N-alkenyl sulfonamides and N-alkenoxyl sulfonamides, which were subjected to different conditions to achieve exo-selective intramolecular bromo-amination, resulting in cyclic bromoamides with high yields and good diastereoselectivities. The analyses used to characterize the products and intermediates included 1H and 13C NMR spectroscopy, infrared (IR) spectroscopy, mass spectrometry (MS), and elemental analysis, providing comprehensive data on the structure and composition of the synthesized compounds.
10.1039/b310519a
The research investigates the cyclodextrin complexation of a stilbene and the self-assembly of a simple molecular device. Key chemicals involved include (E)-4-tert-Butyl-4'-oxystilbene (1'), α-cyclodextrin (αCD), β-cyclodextrin (βCD), N-(6A-deoxy-α-cyclodextrin-6A-yl)-N'-(6A-deoxy-β-cyclodextrin-6A-yl)urea (2), and N,N-bis(6A-deoxy-β-cyclodextrin-6Ayl)urea (3). The study explores how the stilbene 1' can be photoisomerized between its (E) and (Z) isomers, and how these isomers interact with cyclodextrins to form inclusion complexes. The research also examines the formation of binary and ternary complexes, such as 2·(E)-1' and 2·(Z)-1'·4', where 4' represents 4-methylbenzoate. These interactions are studied using techniques like UV-vis spectroscopy and 1H NMR spectroscopy to understand the dynamics of complexation and isomerization, revealing the potential for constructing molecular devices that can be controlled by photochemical and thermal processes.
10.1021/ja00218a036
The research explores the catalytic effects of α-cyclodextrin (CD) on the debromination of 4-alkyl-4-bromo-2,5-cyclohexadienones in aqueous solution. The study aims to understand the role of CD in the debromination process, which is the reverse of the ipso bromination of phenols. The researchers found that CD significantly catalyzes the debromination reaction, with the rate being about 18 times faster in the presence of 5 mM CD. The results suggest that the catalysis involves the reaction of free bromide ion with the CD-dienone complex, and the rate enhancements are much larger (2400-4600) and almost constant, implying that Br- in its CD complex is a stronger nucleophile than bromide ion that is completely solvated by water. The chemicals used in the process include α-cyclodextrin, various alkylphenols (such as methyl, ethyl, isopropyl, n-propyl, and tert-butyl derivatives), bromine, and aqueous solutions of hydrochloric acid and potassium bromide. The conclusions provide insights into the mechanism of CD-catalyzed reactions and the transition state for bromination and debromination, highlighting the strong binding of the transition state to CD and the enhanced nucleophilicity of bromide ion when complexed by CD.
Xi
Xi:Irritant;
