Convenient Preparations of Imines and Symmetrical Secondary Amines Possessing Primary or Secondary Alkyl Groups

Synthesis ◽  
1991 ◽  
Vol 1991 (09) ◽  
pp. 703-708 ◽  
Author(s):  
Alan R. Katritzky ◽  
Xiaohong Zhao ◽  
Gregory J. Hitchings
Keyword(s):  
Secondary Amines ◽  
Alkyl Groups

THE MECHANISM OF THE DEHYDROBROMINATION OF TETRA-O-AGETYL-α-D-GLUGOPYRANOSYL BROMIDE

1965 ◽  
Vol 43 (1) ◽  
pp. 94-105 ◽  
Author(s):  
R. U. Lemieux ◽  
D. R. Lineback
Keyword(s):  
Reaction Time ◽  
Kinetic Study ◽  
Hydrogen Bromide ◽  
Secondary Amines ◽  
Polar Solvents ◽  
Second Stage ◽  
Alkyl Groups

The conversion of tetra-O-acetyl-α-D-glucopyranosyl bromide (I) to 2-acetoxy-D-glucal triacetate (II) was found to be catalyzed by secondary amines containing n-alkyl groups. Substitution at the α-positions of the amine reduced the catalysis. Although triethylamine and tri-n-propylamine did not serve as useful catalysts, the less hindered and strongly basic 1,4-diazabicyclo[2,2,2]octane was more effective than diethylamine. The reaction is strongly promoted by polar solvents and added salts—especially tetra-n-butylammonium bromide. The course of the reaction involves direct elimination of hydrogen bromide and this reaction is in competition with the formation of acetylated N-glucosides. A kinetic study of the reaction using a variety of amines led to the conclusion that the first stage of the reaction is dissociation of I to glycosyloxocarbonium ion strongly solvated by the amine. Depending on the structure of the amine, the second stage of the reaction may involve transfer of the 2-proton to the amine to form 11 at a faster or slower rate than the formation of the N to C1 bond of the acetylated N-glucoside. Conditions were established for the near quantitative conversion of I to II in about 1/100th the reaction time reported in the literature.

Orthoamide, LXIX [1]. Beiträge zur Synthese N,N,N´,N´,N´´-peralkylierter Guanidine und N,N,N´,N´,N´´䞲,N´´-persubstituierter Guanidiniumsalze / Orthoamides, LXIX [1]. Contributions to the Synthesis of N, N, N´, N´, N´-peralkylated Guanidines and N, N, N´, N´, N´´, N´´-persubstituted Guanidinium Salts

2010 ◽  
Vol 65 (7) ◽  
pp. 873-906 ◽  
Author(s):  
Willi Kantlehner ◽  
Jochen Mezger ◽  
Ralf Kreß ◽  
Horst Hartmann ◽  
Thorsten Moschny ◽  
...  
Keyword(s):  
Sodium Hydroxide ◽  
Allyl Chloride ◽  
Dimethyl Sulfate ◽  
Benzyl Bromide ◽  
Ethyl Acrylate ◽  
Secondary Amines ◽  
Butyl Bromide ◽  
Modified Method ◽  
Alkyl Groups ◽  
Guanidinium Salts

N, N, N´, N´-Tetraalkyl-chloroformamidinium chlorides 6 are prepared from N, N, N´, N´-tetraalkylureas 5 and phosgene in acetonitrile. The iminium salts 6 react with primary and secondary amines in the presence of triethylamine to give N, N, N´, N´, N´´-pentasubstituted and N, N, N´, N´, N´´, N´´- hexasubstituted guanidinium salts 7 and 8, respectively, Treatment of the guanidinium salts 7 with sodium hydroxide in excess affords the N, N, N´N´, N´´-pentasubstituted guanidines 9a - 9aa. Additionally, the N, N, N´, N´, N´´-pentasubstituted and N, N, N´, N´, N´´, N´´-hexasubstituted guanidinium salts 7l´, 7p´ and 8a - c can be obtained from the reaction mixtures by addition of stoichiometric amounts of sodium hydroxide. A modified method is described for the preparation of guanidinium salts possessing dialkylamino substituents consisting of two long-chain alkyl groups (>C14). Some guanidines 9 were alkylated with allyl chloride and bromide, ethyl bromide, butyl bromide, benzyl bromide and chloride, dimethyl sulfate, diethyl sulfate, and methyl methansulfonate to give the corresponding guanidinium salts 11 - 15. By alkylation of the N, N, N´, N´, N´´-pentasubstituted guanidine 9v with triethyloxonium tetrafluoroborate the guandinium tetrafluoroborate 16a is accessible. N-Functionalized guanidinium salts 17 - 18a - c result from the reaction of N, N, N´, N´, N´´-pentasubstituted guanidines with ethyl bromoacetate and bromoacetonitrile, respectively, and subsequent anion exchange with sodium tetraphenylborate. N, N, N´, N´-Tetramethylguanidine (21) adds to ethyl acrylate to give the labile guanidine 22, which forms the guanidinium salt 23a on treatment with methyl iodide. Zwitterionic guanidinium salts 25 result, when N, N, N´, N´, N´´-pentasubstituted guanidines are treated with sultones 24.

CATALYZED NITRATION OF AMINES: III. THE EASE OF NITRATION AMONG ALIPHATIC SECONDARY AMINES

1948 ◽  
Vol 26b (1) ◽  
pp. 114-137 ◽  
Author(s):  
G. E. Dunn ◽  
J. C. MacKenzie ◽  
J. W. Suggitt ◽  
George F Wright ◽  
W. J. Chute ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Acetic Anhydride ◽  
Nitrous Acid ◽  
Active Form ◽  
Secondary Amines ◽  
Side Reactions ◽  
Aqua Regia ◽  
Nitryl Chloride ◽  
Alkyl Groups ◽  
Chloride Catalyst

A series of secondary amines, the proton-attracting ability of which had previously been determined, have been converted to their nitramines with nitric acid and acetic anhydride. The gradation in ease of nitration has been found to vary inversely with the proton-attracting ability of the amine. Nitration becomes so difficult at an amine strength corresponding to that of diethanolamine that nitric acid and acetic anhydride alone are ineffective; a chloride catalyst must be used. The amount of this catalyst must be increased as the proton-attracting ability of the amine becomes greater until a full equivalent is required for adequate yield from the strongest amine in the series, diisopropylamine. As the nitration in the series becomes more difficult, side reactions become apparent such as nitrosation, acetylation, and fission of the secondary amine to primary amine and aldehyde. The extent of nitrosation is dependent on the concentration of catalyst, although nitrosation is not catalyzed by presence of chloride. This implies that hydrogen chloride generates nitrous acid in the reaction mixture. Acetylation is independent of presence or concentration of catalyst, but it does not occur during the formation of dicyclohexylnitramine or diisopropylnitramine. This is thought to be owing to steric hindrance from the secondary alkyl groups in these amines. Since nitracidium perchlorate has been found to be ineffective as a catalyst for this nitration, it is doubtful that nitryl chloride is the active form of the catalyst except in so far as it exists in the form of chlorine nitrite. Evidence has accumulated to show that electropositive chlorine is the effective catalyst, and that it is formed by a modification of the aqua regia reaction.

Synthesis under high hydrostatic pressure — a new method to prepare 5,10,15,20-tetrakis[4-(substituted amino)-2,3,5,6-tetrafluorophenyl]porphyrins

2016 ◽  
Vol 20 (08n11) ◽  
pp. 1377-1389 ◽  
Author(s):  
Ana T.P.C. Gomes ◽  
Patrícia C. Freire ◽  
Catarina R.M. Domingos ◽  
Maria G.P.M.S. Neves ◽  
José A.S. Cavaleiro ◽  
...  
Keyword(s):  
High Pressure ◽  
Hydrostatic Pressure ◽  
High Temperatures ◽  
High Hydrostatic Pressure ◽  
Considerable Improvement ◽  
Heterocyclic Amines ◽  
New Method ◽  
Secondary Amines ◽  
Alkyl Groups ◽  
High Yields

5,10,15,20-Tetrakis(pentafluorophenyl)porphyrin reacts with primary alkylamines and heterocyclic amines, at 50°C and under high pressure (450 MPa), to produce the [Formula: see text]-substituted tetraamino derivatives in high yields. Under similar conditions, the reaction with the bulky dibutylamine and dipentylamine affords the corresponding mono-substituted dialkylaminoporphyrins in 10% yield. This new protocol arises as a considerable improvement of the methods already known, which usually require high temperatures and are not effective when using secondary amines having long alkyl groups.

Acceptorless amine dehydrogenation and transamination using Pd-doped layered double hydroxides

2018 ◽  
Author(s):  
Diana Ainembabazi ◽  
Nan An ◽  
Jinesh Manayil ◽  
Kare Wilson ◽  
Adam Lee ◽  
...  
Keyword(s):  
Layered Double Hydroxides ◽  
Oxidation States ◽  
Secondary Amines ◽  
Primary Amines ◽  
Acid Dissolution ◽  
Oxidative Amination ◽  
Strong Function ◽  
Excellent Activity ◽  
High Yields ◽  
Double Hydroxides

<div> <p>The synthesis, characterization, and activity of Pd-doped layered double hydroxides (Pd-LDHs) for for acceptorless amine dehydrogenation is reported. These multifunctional catalysts comprise Brønsted basic and Lewis acidic surface sites that stabilize Pd species in 0, 2+, and 4+ oxidation states. Pd speciation and corresponding cataytic performance is a strong function of metal loading. Excellent activity is observed for the oxidative transamination of primary amines and acceptorless dehydrogenation of secondary amines to secondary imines using a low Pd loading (0.5 mol%), without the need for oxidants. N-heterocycles, such as indoline, 1,2,3,4-tetrahydroquinoline, and piperidine, are dehydrogenated to the corresponding aromatics with high yields. The relative yields of secondary imines are proportional to the calculated free energy of reaction, while yields for oxidative amination correlate with the electrophilicity of primary imine intermediates. Reversible amine dehydrogenation and imine hydrogenation determine the relative imine:amine selectivity. Poisoning tests evidence that Pd-LDHs operate heterogeneously, with negligible metal leaching; catalysts can be regenerated by acid dissolution and re-precipitation.</p> </div> <br>

Electrochemical Vicinal Difluorination of Alkenes: Sustainable, Scalable, and Amenable to Electron-rich Substrates

2019 ◽  
Author(s):  
Sayad Doobary ◽  
Alexi Sedikides ◽  
Henry caldora ◽  
Darren poole ◽  
Alastair Lennox
Keyword(s):  
Bioactive Compounds ◽  
Hypervalent Iodine ◽  
Electrochemical Generation ◽  
Oxidative Decomposition ◽  
Alkyl Groups ◽  
Rich Functionality

Fluorinated alkyl groups are important motifs in bioactive compounds, positively influencing pharmacokinetics, potency and F conformation. The oxidative difluorination of alkenes represents an H important strategy for their preparation, yet current methods are limited in their alkene-types and tolerance of electron-rich, readily oxidized functionalities, as well as in their scalability. Herein, we report a method for the difluorination of a number of unactivated alkene-types that is tolerant of electron-rich functionality, giving products that are otherwise unattainable. Key to success is the electrochemical generation of a hypervalent iodine mediator (in the presence of nucleophilic fluoride and HFIP) using an ‘ex-cell’ approach, which avoids the oxidative decomposition of the substrate. The more sustainable conditions give good to excellent yields of product in up to decagram scales<br>

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