scholarly journals Dinuclear manganese alkoxide complexes as catalysts for C–N bond cleavage of simple tertiary N,N-dialkylamides to give esters

2019 ◽  
Vol 10 (10) ◽  
pp. 2860-2868 ◽  
Author(s):  
Haruki Nagae ◽  
Takahiro Hirai ◽  
Daiki Kato ◽  
Shusei Soma ◽  
Shin-ya Akebi ◽  
...  
Keyword(s):  
Chemical Transformation ◽  
Bond Cleavage ◽  
Lone Pair ◽  
Organic Reactions ◽  
Reaction Conditions ◽  
Amide Bonds ◽  
Nitrogen Lone Pair ◽  
Tertiary Amides ◽  
Strong Acids

Amide bonds are stable due to the resonance between the nitrogen lone pair and the carbonyl moiety, and therefore the chemical transformation of amides, especially tertiary amides, involving C–N bond fission is considered one of the most difficult organic reactions, unavoidably requiring harsh reaction conditions and strong acids or bases.

Characterization and Catalytic Activity of Poly(4-Vinylpyridine-Co-Divinylbenzene)-Co2+ Complex

2005 ◽  
Vol 494 ◽  
pp. 363-368 ◽  
Author(s):  
D. Lončarević ◽  
Ž. Čupić
Keyword(s):  
Catalytic Activity ◽  
Molecular Level ◽  
Supported Catalysts ◽  
Lone Pair ◽  
Polymer Support ◽  
Polymeric Complex ◽  
Reaction Conditions ◽  
Pyridine Nitrogen ◽  
Nitrogen Lone Pair ◽  
Thermal Stability Of

Poly(4-vinylpyridine-co-divinylbenzene)-Co2+ was characterized using infrared spectroscopy (IR), thermogravimetric analysis (TG-DTA), N2-physisorption and polarography. Thermal analysis suggests sufficient thermal stability of the polymer support, under reaction conditions. From polarography measurements, the Co2+ content on polymer-supported catalysts is estimated and it was proved that no significant leaching occurred during the activity tests. At the molecular level, FTIR of P4VP-DVB-Co2+ reveals that the pyridine nitrogen lone pair coordinates to the metal center in the polymeric complex. The obtained P4VP-DVB-Co2+ catalysts performed interesting catalytic activity in reaction of the cyclohexane oxidation with air, indicating that increasing Co2+ content lowers the initiation temperature and raises the decomposition of cyclohexylhydroperoxide.

Cisplatin-Triggered Bioorthogonal Decaging of Amide Bonds for Targeted-Drug Activation in vivo

2018 ◽  
Author(s):  
Benjamin Stenton ◽  
Bruno Oliveira ◽  
João Conde ◽  
Magda Negrão ◽  
Miguel Godinho Ferreira ◽  
...  
Keyword(s):  
Bond Cleavage ◽  
Xenograft Model ◽  
Amide Bonds ◽  
Control Drug ◽  
Tertiary Amide ◽  
Platinum Salts ◽  
First Choice ◽  
Tertiary Amides ◽  
Drug Activation

<p>Creating ways to control drug activation at specific tissues while sparing healthy tissues remains a major challenge. The administration of exogenous triggers offers the possibility for precise and traceless drug activation. However, ensuring localization of the trigger as well as the prodrug at the diseased tissue is complex while essential for therapeutic efficacy and to avoid side-toxicity. Cisplatin remains a first line option to treat 20% of all cancer patients and while clearing after 30 min from blood it concentrates in tumor tissues. Here, we demonstrate the use of the platinum-mediated bond cleavage of protected tertiary amides, which can occur in a catalytic manner under bioorthogonal conditions. Protected analogues of cytotoxic drugs 5-fluorouracil (5-FU) and monomethyl auristatin E (MMAE) were successfully activated using non-toxic amounts of platinum salts in cells. An otherwise fully stable and non-internalizing ADC built using a bifunctional linker featuring a tertiary amide protected MMAE was also bioorthogonally decaged in the presence of platinum salts for extracellular drug release. Finally, cisplatin-mediated activation of a prodrug 5-FU was shown in a colorectal zebrafish xenograft model leading to a significant tumor reduction. Considering cisplatin’s continued use as a first-choice treatment for many solid cancers and especially in colorectal cancer, we anticipate that our platinum-mediated decaging strategy will enhance cancer therapy by allowing tumor specific prodrug activation.</p>

Cisplatin-Triggered Bioorthogonal Decaging of Amide Bonds for Targeted-Drug Activation in vivo

2018 ◽  
Author(s):  
Benjamin Stenton ◽  
Bruno Oliveira ◽  
João Conde ◽  
Magda Negrão ◽  
Miguel Godinho Ferreira ◽  
...  
Keyword(s):  
Bond Cleavage ◽  
Xenograft Model ◽  
Amide Bonds ◽  
Control Drug ◽  
Tertiary Amide ◽  
Platinum Salts ◽  
First Choice ◽  
Tertiary Amides ◽  
Drug Activation

<p>Creating ways to control drug activation at specific tissues while sparing healthy tissues remains a major challenge. The administration of exogenous triggers offers the possibility for precise and traceless drug activation. However, ensuring localization of the trigger as well as the prodrug at the diseased tissue is complex while essential for therapeutic efficacy and to avoid side-toxicity. Cisplatin remains a first line option to treat 20% of all cancer patients and while clearing after 30 min from blood it concentrates in tumor tissues. Here, we demonstrate the use of the platinum-mediated bond cleavage of protected tertiary amides, which can occur in a catalytic manner under bioorthogonal conditions. Protected analogues of cytotoxic drugs 5-fluorouracil (5-FU) and monomethyl auristatin E (MMAE) were successfully activated using non-toxic amounts of platinum salts in cells. An otherwise fully stable and non-internalizing ADC built using a bifunctional linker featuring a tertiary amide protected MMAE was also bioorthogonally decaged in the presence of platinum salts for extracellular drug release. Finally, cisplatin-mediated activation of a prodrug 5-FU was shown in a colorectal zebrafish xenograft model leading to a significant tumor reduction. Considering cisplatin’s continued use as a first-choice treatment for many solid cancers and especially in colorectal cancer, we anticipate that our platinum-mediated decaging strategy will enhance cancer therapy by allowing tumor specific prodrug activation.</p>

Structure and bonding in cyclic phosphoramidates as determined by carbon-13 magnetic resonance

1979 ◽  
Vol 57 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Gerald W. Buchanan ◽  
Frederick G. Morin
Keyword(s):  
Magnetic Resonance ◽  
Nitrogen Atom ◽  
Electron Pair ◽  
Chemical Shifts ◽  
Lone Pair ◽  
Ring Conformation ◽  
Delocalized Electron ◽  
Nitrogen Lone Pair ◽  
Structure And Bonding

13C chemical shifts and 13C–31P couplings are reported for 11 cyclic phosphoramidates of ring sizes from four to nine. Vicinal couplings are compared with those of carbocyclic analogs and provide insight regarding the degree of nitrogen lone pair derealization into the N—P bond. For six-membered and larger rings, there appears to be nearly complete lone pair delocalization, i.e., a trigonal planar nitrogen atom. In azetidine derivatives the nitrogen lone pair remains localized, giving rise to a highly puckered ring conformation. Pyrrolidine derivatives are viewed as having a nitrogen with a partially delocalized electron pair.

scholarly journals The N-atom in [N(PR3)2]+ cations (R = Ph, Me) can act as electron donor for (pseudo) anti-electrostatic interactions

CrystEngComm ◽  
2015 ◽  
Vol 17 (20) ◽  
pp. 3768-3771 ◽  
Author(s):  
Antonio Bauzá ◽  
Antonio Frontera ◽  
Tiddo J. Mooibroek ◽  
Jan Reedijk
Keyword(s):  
Hydrogen Bonding ◽  
Electron Donor ◽  
Molecular Hydrogen ◽  
Electrostatic Interactions ◽  
Lone Pair ◽  
Dft Study ◽  
Nitrogen Lone Pair

A CSD analysis and DFT study reveal that the nitrogen lone-pair in [N(PPh3)2]+ is partially intact and involved in intramolecular hydrogen bonding.

A Discussion on photoelectron spectroscopy - Orderings of π and σ ionization potentials in carbocyclic and heterocyclic aromatic compounds

1970 ◽  
Vol 268 (1184) ◽  
pp. 131-140 ◽  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Aromatic Compounds ◽  
Lone Pair ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Light Sources ◽  
Orbital Energies ◽  
Substituted Pyridines ◽  
Nitrogen Lone Pair ◽  
Electron Correlation Effects

Data on calculated orbital energies and experimentally measured ionization potentials of carbocyclic and heterocyclic aromatic compounds are compared and contrasted. The ordering or orbital energies and ionization potentials do not always seem to parallel one another, probably owing to either electron correlation effects, or to deviations from Koopman’s theorem. The effects on photoelectron spectra of using different light sources and analysers are discussed in relation to their bearing on the orbital orderings of aromatic compounds. The high resolution He 584 A. photoelectron spectrum of pyridine is shown to be open to two interpretations regarding the ordering of the ionization potentials of the π orbitals and the ‘nitrogen lone pair’ (n). One of the interpretations involves the three lowest pyridine ionization potentials being π (9.2 eV), π L (9.5 eV) and n (10.5 eV) whilst the other has the first three ionization potentials being the order π , n, π . The photoelectron spectra of substituted pyridines and diazines are discussed in the light of the two possible explanations for the pyridine spectrum.

ChemInform Abstract: STUDIES ON NITROGEN LONE - PAIR ORIENTATION AND NONBONDED N-PI INTERACTION IN N-HETEROCYCLIC COMPOUNDS

1975 ◽  
Vol 6 (22) ◽  
pp. no-no
Author(s):  
I. MORISHIMA ◽  
K. YOSHIKAWA ◽  
K. TOYODA ◽  
K. BEKKI ◽  
S. SAKATA ◽  
...  
Keyword(s):  
Heterocyclic Compounds ◽  
Lone Pair ◽  
Nitrogen Lone Pair

scholarly journals Selective C-N σ Bond Cleavage in Azetidinyl Amides under Transition Metal-Free Conditions

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 459 ◽  
Author(s):  
Hengzhao Li ◽  
Zemin Lai ◽  
Adila Adijiang ◽  
Hongye Zhao ◽  
Jie An
Keyword(s):  
Electron Transfer ◽  
Transition Metal ◽  
Transfer Reaction ◽  
Bond Cleavage ◽  
Electron Transfer Reaction ◽  
Amide Bond ◽  
Single Electron Transfer ◽  
Reaction Conditions ◽  
Metal Free ◽  
Single Electron Transfer Reaction

Functionalization of amide bond via the cleavage of a non-carbonyl, C-N σ bond remains under-investigated. In this work, a transition-metal-free single-electron transfer reaction has been developed for the C-N σ bond cleavage of N-acylazetidines using the electride derived from sodium dispersions and 15-crown-5. Of note, less strained cyclic amides and acyclic amides are stable under the reaction conditions, which features the excellent chemoselectivity of the reaction. This method is amenable to a range of unhindered and sterically encumbered azetidinyl amides.

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