- Selective Synthesis of Bisdimethylamine Derivatives from Diols and an Aqueous Solution of Dimethylamine through Iridium-Catalyzed Borrowing Hydrogen Pathway
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Bisdimethylamine derivatives are an important class of compounds in the polymer and pharmaceutical industries. However, existing methods for the synthesis of these compounds have several drawbacks such as low selectivity, use of toxic reagents, and generation of waste. In this study, a new system was developed for the selective synthesis of bisdimethylamine derivatives using a diol and dimethylamine as starting materials and an iridium complex bearing an N-heterocyclic carbene ligand as catalyst. The starting materials were easily available, less toxic, inexpensive, and easy to handle. The reaction proceeded efficiently through a borrowing hydrogen pathway under aqueous conditions, without any additional organic solvent, to afford various bisdimethylamine derivatives in good to excellent yields.
- Fujita, Ken-ichi,Jeong, Jaeyoung
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- Reduction of Amides to Amines under Mild Conditions via Catalytic Hydrogenation of Amide Acetals and Imidates
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A simple and general protocol was developed for selective conversion of amides into amines. Amides were converted into amide acetals and imido esters by O-alkylation and then hydrogenated without isolation into amines under very mild reaction conditions over standard hydrogenation catalysts. Triethyloxonium tertafluoroborate, methyl trifluoromethanesulfonate, dimethyl sulfate and ethyl chloroformate were validated as alkylating agent. The synthetic utility of this approach was demonstrated by the selective carbonyl reduction of peptide groups. Carbonyl reduction of peptide group proceeds chemoselective without racemization of the neighboring chiral center. (Figure presented.).
- Kadyrov, Renat
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p. 185 - 191
(2018/11/23)
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- Catalytic Hydrogenation for Producing Amines from Carboxylic Acid Amides, Carboxylic Acid Diamides, Di-, Tri-, or Polypeptides, or Peptide Amides
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The present invention relates to a process for the preparation of amines, comprising the following steps: a. reaction of a (i) carboxylic acid amide of the general formula (I), or (ii) carboxylic acid diamide of the general formula (II), or (iii) di-, tri- or polypeptide, or (iv) peptide amide with carboxy-terminal amide function with an alkylating agent, b. addition of a hydrogenation catalyst to the reaction mixture in a molar ratio of from 1:10 to 1:100 000, based on carboxylic acid amide, carboxylic acid diamide, di-, tri- or polypeptide or peptide amide, c. reaction of the reaction mixture with hydrogen, where a hydrogen pressure of from 0.1 bar to 200 bar is established and where a temperature in a range of from 0° C. to 250° C. is established.
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Paragraph 187-189
(2016/10/11)
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- Antibacterial and Antibiofilm Activity of Cationic Small Molecules with Spatial Positioning of Hydrophobicity: An in Vitro and in Vivo Evaluation
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More than 80% of the bacterial infections are associated with biofilm formation. To combat infections, amphiphilic small molecules have been developed as promising antibiofilm agents. However, cytotoxicity of such molecules still remains a major problem. Herein we demonstrate a concept in which antibacterial versus cytotoxic activities of cationic small molecules are tuned by spatial positioning of hydrophobic moieties while keeping positive charges constant. Compared to the molecules with more pendent hydrophobicity from positive centers (MIC = 1-4 μg/mL and HC50 = 60-65 μg/mL), molecules with more confined hydrophobicity between two centers show similar antibacterial activity but significantly less toxicity toward human erythrocytes (MIC = 1-4 μg/mL and HC50 = 805-1242 μg/mL). Notably, the optimized molecule is shown to be nontoxic toward human cells (HEK 293) at a concentration at which it eradicates established bacterial biofilms. The molecule is also shown to eradicate preformed bacterial biofilm in vivo in a murine model of superficial skin infection.
- Hoque, Jiaul,Konai, Mohini M.,Sequeira, Shanola S.,Samaddar, Sandip,Haldar, Jayanta
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p. 10750 - 10762
(2016/12/16)
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- Cleavable cationic antibacterial amphiphiles: Synthesis, mechanism of action, and cytotoxicities
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The development of novel antimicrobial agents having high selectivity toward bacterial cells over mammalian cells is urgently required to curb the widespread emergence of infectious diseases caused by pathogenic bacteria. Toward this end, we have developed a set of cationic dimeric amphiphiles (bearing cleavable amide linkages between the headgroup and the hydrocarbon tail with different methylene spacers) that showed high antibacterial activity against human pathogenic bacteria (Escherichia coli and Staphylococcus aureus) and low cytotoxicity. The Minimum Inhibitory Concentrations (MIC) were found to be very low for the dimeric amphiphiles and were lower or comparable to the monomeric counterpart. In the case of dimeric amphiphiles, MIC was found to decrease with the increase in the spacer chain length (n = 2 to 6) and again to increase at higher spacer length (n > 6). It was found that the compound with six methylene spacers was the most active among all of the amphiphiles (MICs = 10-13 μM). By fluorescence spectroscopy, fluorescence microscopy, and field-emission scanning electron microscopy (FESEM), it was revealed that these cationic amphiphiles interact with the negatively charged bacterial cell membrane and disrupt the membrane integrity, thus killing the bacteria. All of the cationic amphiphiles showed low hemolytic activity (HC50) and high selectivity against both gram-positive and gram-negative bacteria. The most active amphiphile (n = 6) had a 10-13-fold higher HC50 than did the MIC. Also, this amphiphile did not show any cytotoxicity against mammalian cells (HeLa cells) even at a concentration above the MIC (20 μM). The critical micellar concentration (CMC) values of gemini surfactants were found to be very low (CMC = 0.30-0.11 mM) and were 10-27 times smaller than the corresponding monomeric analogue (CMC = 2.9 mM). Chemical hydrolysis and thermogravimetric analysis (TGA) proved that these amphiphiles are quite stable under both acidic and thermal conditions. Collectively, these properties make the newly synthesized amphiphiles potentially superior disinfectants and antiseptics for various biomedical and biotechnological applications.
- Hoque, Jiaul,Akkapeddi, Padma,Yarlagadda, Venkateswarlu,Uppu, Divakara S. S. M.,Kumar, Pratik,Haldar, Jayanta
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p. 12225 - 12234
(2012/11/07)
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- Stable-isotope dimethylation labeling combined with LC-ESI MS for quantification of amine-containing metabolites in biological samples
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One of the challenges associated with metabolome profiling in complex biological samples is to generate quantitative information on the metabolites of interest. In this work, a targeted metabolome analysis strategy is presented for the quantification of amine-containing metabolites. A dimethylation reaction is used to introduce a stable isotopic tag onto amine-containing metabolites followed by LC-ESI MS analysis. This labeling reaction employs a common reagent, formaldehyde, to label globally the amine groups through reductive animation. The performance of this strategy was investigated in the analysis of 20 amino acids and 15 amines by LC-ESI MS. It is shown that the labeling chemistry is simple, fast (13C-dimethylation does not show any isotope effect on either RPLC or HILIC LC, indicating that 13C-labeling is a preferred approach for relative quantification of amine-containing metabolites in different samples. The isotopically labeled 35 amine-containing analogues were found to be stable and proved to be effective in overcoming matrix effects in both relative and absolute quantification of these analytes present in a complicated sample, human urine. Finally, the characteristic mass difference provides additional structural information that reveals the existence of primary or secondary amine functional groups in amine-containing metabolites. As an example, for a human urine sample, a total of 438 pairs of different amine-containing metabolites were detected, at signal-to-noise ratios of greater than 10, by using the labeling strategy in conjunction with RP LC-ESI Fourier-transform ion cyclotron resonance MS.
- Guo, Kevin,Ji, Chengjie,Li, Liang
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p. 8631 - 8638
(2008/03/15)
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- Base-promoted elimination reactions of acetaldehyde N-alkyl-N,N-dimethylhydrazonium salts. A convenient synthesis of N,N-dimethylalkylamines
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The title reaction was utilized for efficient conversion of S(N)2-reactive alkyl halides to the corresponding N,N-dimethylalkylamines.
- Smith,Marcucci,Tingue
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p. 381 - 389
(2007/10/02)
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