Synthesis of Unsymmetrical Diarylureas via Pd-Catalyzed C–N Cross-Coupling Reactions
摘要:
A facile synthesis of unsymmetrical N,N'-diarylureas is described. The utilization of the Pd-catalyzed arylation of ureas enables the synthesis of an array of diarylureas in good to excellent yields from benzylurea via a one-pot arylation-deprotection protocol, followed by a second arylation.
Brahmachari et al., Journal of the Indian Chemical Society, 1931, vol. 8, p. 315
作者:Brahmachari et al.
DOI:——
日期:——
Measurement of 15N enrichment of glutamine and urea cycle amino acids derivatized with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate using liquid chromatography–tandem quadrupole mass spectrometry
6-Aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) is an amino acid-specific derivatizing reagent that has been used for sensitive amino acid quantification by liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS). In this study, we aimed to evaluate the ability of this method to measure the isotopic enrichment of amino acids and to determine the positional N-15 enrichment of urea cycle amino acids (i.e., arginine, omithine, and citrulline) and glutamine. The distribution of the M and M + 1 isotopomers of each natural AQC-amino acid was nearly identical to the theoretical distribution. The standard deviation of the (M + 1)/M ratio for each amino acid in repeated measurements was approximately 0.1%, and the ratios were stable regardless of the injected amounts. Linearity in the measurements of N-15 enrichment was confirmed by measuring a series of N-15-labeled arginine standards. The positional N-15 enrichment of urea cycle amino acids and glutamine was estimated from the isotopic distribution of unique fragment ions generated at different collision energies. This method was able to identify their positional N-15 enrichment in the plasma of rats fed 15N-labeled glutamine. These results suggest the utility of LC-MS/MS detection of AQC-amino acids for the measurement of isotopic enrichment in N-15-labeled amino acids and indicate that this method is useful for the study of nitrogen metabolism in living organisms. (C) 2015 Elsevier Inc. All rights reserved.