A novel class of stable, mild, and size-shape-selective nitrosating agents for secondary amides is introduced. These are based on reversible entrapment and release of reactive nitrosonium species by calix[4]arenes. The NO+ encapsulation controls the reaction selectivity.
The Selective<i>N</i>-Monoalkylation of Amides with Alkyl Halides in the Presence of Alumina and KOH
作者:Kazuaki Sukata
DOI:10.1246/bcsj.58.838
日期:1985.3
The effects of alumina impregnated with KOH (KOH/Al2O3) and a mixture of alumina and powdered KOH (KOH+Al2O3) have been examined using the alkylation of benzamide under various conditions. In each case, alkylation occurs exclusively in the pores of the alumina, the extent depending upon the alumina-pore size. For both yield and selectivity for N-monoalkylation, KOH+Al2O3 is superior to KOH/Al2O3. Dioxane is the best of the solvents employed. It is proposed that, in dioxane, an enolate-like species, (Remark: Graphics omitted.), exists as stable ion-pair aggregates, which are the true reactants in the pore. This method, using KOH/Al2O3 or KOH+Al2O3, has been applied to N-alkylation of the other amides, giving the N-monoalkylated products in substantial yields with extremely high selectivities. 2-Phenylacetamide is regioselectively N-monoalkylated in high yields. This regioselectivity is explained in terms of steric hindrance.
Efficienttransamidation of unactivated carboxamides, phthalimides, formamides and thioamides with amines undersolvent-freeconditions using H-β-zeolite as a green and recyclable heterogeneous catalyst is described. Easy work up, high purity of the products, recyclability and environmentally-friendly nature of the catalyst are the attractive features of the present methodology. This is the first report
Aromatic Cation Activation: Nucleophilic Substitution of Alcohols and Carboxylic Acids
作者:Thanh V. Nguyen、Alp Bekensir
DOI:10.1021/ol5003972
日期:2014.3.21
A new method for the nucleophilicsubstitution of alcohols and carboxylic acids using aromatic tropylium cation activation has been developed. This article reports the use of chloro tropylium chloride for the rapid generation of alkyl halides and acyl chlorides under very mild reaction conditions. It demonstrates, for the first time, the synthetic potential of tropylium cations in promoting chemical
A highly improved and green methodology for the direct amidation of carboxylic acids with amines using silica gel as a solidsupport and catalyst is described. The scope of this...
描述了使用硅胶作为固体载体和催化剂将羧酸与胺直接酰胺化的高度改进的绿色方法。这个范围...
C–N Coupling of Amides with Alcohols Catalyzed by N-Heterocyclic Carbene–Phosphine Iridium Complexes
作者:Sutthichat Kerdphon、Xu Quan、Vijay Singh Parihar、Pher G. Andersson
DOI:10.1021/acs.joc.5b01324
日期:2015.11.20
N-Heterocycliccarbene–phosphineiridiumcomplexes (NHC–Ir) were developed/found to be a highly reactive catalyst for N-monoalkylation of amides with alcohols via hydrogen transfer. The reaction produced the desired product in high isolated yields using a wide range of substrates with low catalyst loading and short reaction times.