Utilization of lithium triethylborohydride as a selective N-acyl deprotecting agent
摘要:
Lithium triethylborohydride has been found to be a superior and selective reagent for the removal of tertiary N-acyl protecting groups. The reagent selectively removes tertiary amide acyl functionality without affecting secondary amide functionality even when they are present in the same molecule. Some tertiary carbamates may be also removed under the same conditions. (C) 2002 Published by Elsevier Science Ltd.
Efficient and selective N-alkylation of carbamates in the presence of Cs2CO3 and TBAI
摘要:
Mild and selective N-alkylation of carbamates was carried our in the presence of cesium carbonate, tetra-butylammonium iodide (TBAI), and a halide. This protocol was highly selective and efficient, offering aliphatic and aromatic N-alkyl carbamates exclusively in high yields. (C) 2001 Published by Elsevier Science Ltd.
or carbon nanotubes were investigated in a reaction between alkyl halides, amines, and CO2. The yield of carbamates was up to 85 % at 100 °C and 1 MPa of CO2 after 3 h (first stage 25 °C, 1 h) in the presence of Cs2CO3 and DMF as a solvent. The best results were achieved in the case of large ammonium substituents (C4 and C6) in the catalyst, benzyl amine, and benzyl chloride as reagents. The catalysts
The reaction of n,n-dibenzylcarbamoyl chloride with n-nitrosohydroxylamine
作者:Masayuki Nakajima、Jean-Pierre Anselme
DOI:10.1016/s0040-4039(00)99823-x
日期:1984.1
The action of N,N-dibenzylcarbamoyl chloride (2) on the sodium salt of N-nitrosohydroxylamines (1) in dry acetonitrile at reflux leads to products whose formation may be rationalized in terms of carbamoylation at either oxygen of the bidentate N-nitrosohydroxylamines.
An efficient and chemoselective Cbz-protection of amines using silica–sulfuric acid at room temperature
作者:Manoj B. Gawande、Vivek Polshettiwar、Rajender S. Varma、Radha V. Jayaram
DOI:10.1016/j.tetlet.2007.09.091
日期:2007.11
A simple, facile, and chemoselective N-benzyloxycarbonylation of amines using silica-sulfuric acid that proceeds under solvent-free conditions at room temperature has been achieved. These reactions are applicable to a wide variety of primary (aliphatic and cyclic) secondary amines, amino alcohols, and heterocyclic amines. (c) 2007 Elsevier Ltd. All rights reserved.
NAKAJIMA, MASAYUKI;ANSELME, J. -P., TETRAHEDRON LETT., 1984, 25, N 2, 139-140