- Benzhydrylamine: An effective aminating agent for the synthesis of primary amines
-
Aldehydes, ketones, alkyl toluene-p-sulfonates and halides are converted into the corresponding primary amines with benzhydrylamine as a valuable ammonia synthon in moderate to excellent yields.
- Sun, Quan-Wei,Xing, Jun-De,Qin, Yu-Hong,Yin, Xu-Wen,Zhou, Yi
-
p. 181 - 183
(2018/05/26)
-
- Reduced reactivity of amines against nucleophilic substitution via reversible reaction with carbon dioxide
-
The reversible reaction of carbon dioxide (CO2) with primary amines to form alkyl-ammonium carbamates is demonstrated in this work to reduce amine reactivity against nucleophilic substitution reactions with benzophenone and phenyl isocyanate. The reversible formation of carbamates has been recently exploited for a number of unique applications including the formation of reversible ionic liquids and surfactants. For these applications, reduced reactivity of the carbamate is imperative, particularly for applications in reactions and separations. In this work, carbamate formation resulted in a 67% reduction in yield for urea synthesis and 55% reduction for imine synthesis. Furthermore, the amine reactivity can be recovered upon reversal of the carbamate reaction, demonstrating reversibility. The strong nucleophilic properties of amines often require protection/de-protection schemes during bi-functional coupling reactions. This typically requires three separate reaction steps to achieve a single transformation, which is the motivation behind Green Chemistry Principle #8: Reduce Derivatives. Based upon the reduced reactivity, there is potential to employ the reversible carbamate reaction as an alternative method for amine protection in the presence of competing reactions. For the context of this work, CO2 is envisioned as a green protecting agent to suppress formation of n-phenyl benzophenoneimine and various n-phenyl-n-alky ureas.
- Mohammed, Fiaz S.,Kitchens, Christopher L.
-
-
- Oxidative deprotection of diphenylmethylamines
-
(formula presented) The diphenylmethyl amino protecting group can be efficiently removed by initial oxidation of the amine to an imine by 2,3-dichloro-5,6-dicyanobenzoquinone. The resulting imine can then be easily hydrolyzed under mildly acidic conditions. This method is particularly well suited for the preparation of α-amino phosphinates and α-amino phosphonates.
- Sampson, Peter B.,Honek, John F.
-
p. 1395 - 1397
(2008/02/09)
-
- PREPARATION OF AN ELECTROPHILIC GLYCINE CATION EQUIVALENT AND ITS REACTION WITH HETEROATOM NUCLEOPHILES
-
A variety of heteroatom substituted Schiff base amino esters 4-7 are prepared either from the benzophenone imine of glycine ethyl ester (3) or by reaction of acetate 4 with heteroatom nucleophiles.
- O'Donnell, Martin J.,Bennett, William D.,Polt, Robin L.
-
p. 695 - 698
(2007/10/02)
-
- Mass Spectrometric Investigation of Nitrogen Compounds, XXXV. Phenyl-substituted 2-Azaallenium Ions in the Gas Phase
-
The gas phase chemistry of metastable phenyl-substituted 2-azaallenium ions (2a, b, c) is characterized by intramolecular electrophilic substitution reactions; these processes are energetically favoured in comparison with various phenyl and hydrogen migrations, in spite of the fact that the latter may give rise to the formation of more stable intermediates (nitrilium ions).As a direct consequence of the electrophilic substitution, 2a, c decompose via loss of HCN, whereas from 2b PhCN is eliminated unimolecularly.The combination of experimental investigations, employing - and -labelled precursors, and MNDO calculations allows to give a detailed description of the chemistry of isolated 2a, b, c cations.
- Wuerthwein, Ernst-Ullrich,Halim, Herman,Schwarz, Helmut,Nibbering, Nico M. M.
-
p. 2626 - 2634
(2007/10/02)
-
- INTRAMOLECULAR GENERAL-BASE CATALYSIS OF SCHIFF-BASED HYDROLYSIS BY TERTIARY AMINO GROUPS.
-
Hydrolysis of a series of Schiff bases derived from benzophenone and various amines has been studied kineticlly in aqueous solution. A linear correlation of the log of the rate constants for the water reaction with the Schiff base pK//a (slope minus 0. 70) shows large positive deviations for Schiff bases derived from (2-aminoethyl)diethylamine, N-(2-aminoethyl)morpholine, N-(2-aminoethyl)piperazine and 2-(aminomethyl)pyridine (1i) but small deviations for Schiff bases from N-(3-aminopropyl)morpholine and 2-(2-aminoethyl)pyridine. The deviations found are attributed to intramolecular general-base catalysis of the water reaction by the internal tertiary amino groups. Magnitudes of the rate enhancement are correlated well with pK//a//l of the internal catalyst ( beta equals 0. 49). Effective concentrations of the internal bases are estimated to range from 340 (1e) to 40 M.
- Okuyama,Shibuya,Fueno
-
p. 730 - 736
(2007/10/02)
-