Rapid Conventional and Microwave-Assisted Decarboxylation of L-Histidine and Other Amino Acids via Organocatalysis with R-Carvone Under Superheated Conditions
摘要:
This article reports a new methodology taking advantage of superheated chemistry via either microwave or conventional heating for the facile decarboxylation of alpha amino acids using the recoverable organocatalyst, R-carvone. The decarboxylation of amino acids is an important synthetic route to biologically active amines, and traditional methods of amino acid decarboxylation are time consuming (taking up to several days in the case of L-histidine), are narrow in scope, and make use of toxic catalysts. Decarboxylations of amino acids including L-histidine occur in just minutes while replacing toxic catalysts with green catalyst, spearmint oil. Yields are comparable to or exceed previous methods and purification of product ammonium chloride salts is aided by an isomerization reaction of residual catalyst to phenolic carvacrol. The method has been shown to be effective for the decarboxylations of a range of natural, synthetic, and protected amino acids.
Substituent effects. 14. Anomalous dissociation constants in water-organic solvent mixtures: Benzylammonium ions and related systems
作者:A. J. Hoefnagel、R. H. de Vos、B. M. Wepster
DOI:10.1002/recl.19921110103
日期:——
Thermodynamic dissociation constants in various water-organic solvent mixtures are given for benzylammonium, benzyldialkylammonium, and (2-phenylethyl)ammonium ions. Deviations from the Hammett equation (Eqn. 1) are similar to those observed for carboxylic acids, but of opposite sign. The extended Hammett equation (Eqn. 3), containing the hydrophobic constant, π, yields good correlations. Derived secondary
A rotaxane consisting of a cucurbituril and an uncharged guest molecule, having low or null affinity therebetween is provided as well as processes for providing the same. Various uses as energy converters (“frictionless” molecular motors), biochips and biosensors using the same are also provided.
The present invention is in the field of medicine, particularly in the treatment of Type II diabetes and obesity. More specifically, the present invention relates to selective &bgr;3 receptor agonists useful in the treatment of Type II diabetes and obesity. The invention provides compounds and methods of treating Type II diabetes and obesity, comprising administering to a mammal in need thereof compounds of formula (I) or a pharmaceutically acceptable salt thereof. The variables of formula (I) have the meanings defined herein.
A practical large-scale synthesis was developed for the preparation of N,N′-bis(4,6-disubstituted 1,3,5-triazin-2-yl)-4-aminophenethylamine derivatives exemplified by compound 2. This route is a six-step procedure starting from commercially available cyanuricchloride and 3-(tert-butoxycarbonylamino) aniline based on the reactivity differences of the three chlorine atoms on the triazine ring. The optimized
A rotaxane consisting of a cucurbituril and an uncharged guest molecule, having low or null affinity therebetween is provided as well as processes for providing the same. Various uses as energy converters (“frictionless” molecular motors), biochips and biosensors using the same are also provided.