Activation of Electrophilicity of Stable Y-Delocalized Carbamate Cations in Intramolecular Aromatic Substitution Reaction: Evidence for Formation of Diprotonated Carbamates Leading to Generation of Isocyanates
idea that further protonation of the O-protonated carbamates is involved in the cyclization, but the concentration of the dications is very low and suggests that the rate-determining step is dissociation of methanol from the diprotonated carbamate to generate protonated isocyanate, which reacts with the aromatic ring. Therefore, O-protonated carbamates are weak bases in sharp contrast to other Y-shaped
Synthesis of Methyl Carbamates from Primary Aliphatic Amines and Dimethyl Carbonate in Supercritical CO<sub>2</sub>: Effects of Pressure and Cosolvents and Chemoselectivity
selectivity is observed with polar protic media (i.e., MeOH), plausibly because of solvation effects (through H-bonds) of RNHCO2- moieties. The reaction shows also a good chemoselectivity: bifunctional aliphaticamines bearing either aromatic NH2 or OH substituents [XC6H4(CH2)nNH2, X = NH2, OH; n = 1, 2], undergo methoxycarbonylation reactions exclusively at aliphatic amino groups and give the corresponding
Derivatives of 2-arylimino-2,3-dihydrothiazoles, their preparation processes and their therapeutic use
申请人:Moinet Christophe
公开号:US20070043095A1
公开(公告)日:2007-02-22
The present invention is drawn to compounds of the formula
in racemic and enantiomeric form or all combinations of these forms wherein the various substituents are as defined in the application which compounds have a good affinity for certain subtypes of somatostatin receptors and have useful pharmacological properties.