Unusual formation of sterically hindered primary amines in a series of pyrrolo- and pyrido[1,2-a]indoles

1991 ◽  
Vol 56 (11) ◽  
pp. 2278-2287 ◽  
Author(s):  
Ivo Jirkovsky ◽  
Lynne Greenblatt ◽  
Reinhardt Baudy
Keyword(s):  
Pyridine Ring ◽  
Primary Amines ◽  
Amino Group ◽  
Sterically Hindered ◽  
Similar Preparation ◽  
Unusual Formation

2,3-Dihydro-2,2,9-trimethyl-1H-pyrrolo[1,2-a]indol-1-amine and its 1-(1-pyrrolidinyl) analog have been synthesized from the corresponding 1-ol via mesylation in pyridine followed by treatment with pyrrolidine. Mechanisms of the former, unexpected amination are briefly discussed. Evidence is presented that the pyridine ring serves as a masked amino group. The phenomenon is partly attributed to steric congestion. Similar preparation of 2-bromo-6,7,8,9-tetrahydro-8,8,10-trimethylpyridol[1,2-a]indol-9-amine supports this notion.

Hydrogen Bonding in organic compounds. 1. o-Nitroanilines

1958 ◽  
Vol 11 (4) ◽  
pp. 513 ◽  
Author(s):  
LK Dyall ◽  
AN Hambly
Keyword(s):  
Hydrogen Bonding ◽  
Nitro Group ◽  
Organic Compounds ◽  
Intramolecular Hydrogen Bonding ◽  
Amino Group ◽  
Infra Red ◽  
Sterically Hindered ◽  
Intramolecular Hydrogen

The infra-red spectra of o-nitroanilines do not indicate any intramolecular hydrogen bonding unless there are nitro groups in both positions 2 and 6 to the amino group. An examination of the literature shows that there is no unambiguous evidence from other sources of such bonding in simple o-nitroanilines. An explanation is given of the variation of the stretching frequencies of the nitro group in sterically hindered compounds and in those with electron-donating ortho- and para-substituents.

A general synthesis of 5,7-diaminoimidazo[4,5-b]pyridine ribosides ("2-amino-1-deazaadenosines") from 5-amino-4-imidazolecarboxamide riboside (AICA riboside)

1992 ◽  
Vol 70 (5) ◽  
pp. 1288-1295 ◽  
Author(s):  
John E. Francis ◽  
Michael A. Moskal
Keyword(s):  
Pyridine Ring ◽  
Sodium Hydride ◽  
Ring System ◽  
Ring Closure ◽  
Protecting Groups ◽  
Amino Group ◽  
Phosphoryl Chloride ◽  
Compound A ◽  
General Synthesis ◽  
Methyl Analog

A short general synthesis of 5-substituted 5,7-diaminoimidazo[4,5-b]pyridines from 5-amino-4-imidazolecarboxamide riboside (AICA riboside) was designed to prepare isosteres of substituted 2-aminoadenosines that are selective adenosine A2 receptor agonists. AICA riboside was converted to a hydroxyl-protected 5-amino-4-imidazolecarbonitrile riboside and reacted with an N,N-disubstituted acetamide in the presence of phosphoryl chloride. Sodium hydride treatment completed the ring closure and introduced the 7-amino group. The hydroxyl protecting groups were removed under standard conditions. N-Substitution of the acetamide by one benzyl moiety led to a 5-N-substituted derivative through hydrogenolysis whereas N,N-dibenzylacetamide led to the 5,7-diamino compound. A 6-methyl analog was obtained from an N,N-disubstituted propionamide. This synthesis may be adapted to other heterocyclic systems, as illustrated by the preparation of an example of the imidazo[4,5-b]pyrrolo[3,2-e]pyridine ring system.

The Palladium-Catalyzed Heteroarylation of Adamantylalkyl Amines with Dihalogenopyridines: Scope and Limitations

Synthesis ◽  
2017 ◽  
Vol 49 (22) ◽  
pp. 5067-5080 ◽  
Author(s):  
Irina Beletskaya ◽  
Anton Abel ◽  
Alexei Averin ◽  
Alexei Buryak ◽  
Evgenii Savelyev ◽  
...  
Keyword(s):  
Chlorine Atom ◽  
Pyridine Ring ◽  
Bromine Atom ◽  
Amino Group ◽  
Halogen Atoms ◽  
Palladium Catalyzed ◽  
Selective Substitution ◽  
Steric Hindrances

Palladium-catalyzed heteroarylation of adamantylalkyl amines characterized by different steric hindrances at the amino group was carried out using 2,3-, 2,5-, 2,6-, and 3,5-dihalogenopyridines. The dependence of the results of the coupling on the nature of the halogen atoms (bromine, chlorine), their position in the pyridine ring, and on the structure of adamantylalkyl amines was investigated. The application of dichloropyridines or bromochloropyridines was shown to be advantageous over the use dibromopyridines in many cases. Selective substitution of bromine atom in positions 3 and 5 in the presence of chlorine atom in position 2 of the pyridine ring was observed. The possibility of N,N-diheteroarylation of adamantane-containing amines with 2,5-dihalogenopyridines was shown, and diamination of 2,6- and 3,5-dihalogenopyridines was demonstrated.

scholarly journals Push or Pull for a Better Selectivity? A Study on the Electronic Effects of Substituents of the Pyridine Ring on the Enantiomeric Recognition of Chiral Pyridino-18-Crown-6 Ethers

Symmetry ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1795
Author(s):  
Balázs Szemenyei ◽  
Balázs Novotny ◽  
Sarolta Zsolnai ◽  
Zsombor Miskolczy ◽  
László Biczók ◽  
...  
Keyword(s):  
Crown Ether ◽  
Pyridine Ring ◽  
Optically Active ◽  
Primary Amines ◽  
Titration Calorimetry ◽  
Synthetic Route ◽  
Electronic Effects ◽  
Enantiomeric Recognition ◽  
Electronic Effects Of Substituents ◽  
Discriminating Ability

Seven dimethyl-substituted optically active pyridino-18-crown-6 ethers containing various substituents at position 4 of the pyridine ring were studied with regards to the electron-donating and -withdrawing effects of substituents on enantiomeric recognition. In order to compile this set of compounds, we prepared four novel pyridino-18-crown-6 ethers, including an intermediate of a new synthetic route for a formerly reported crown ether. The discriminating ability of these pyridino-crown ethers with C2-symmetry toward the enantiomers of protonated primary amines was examined by isothermal titration calorimetry.

scholarly journals Further enhancement of the clickability of doubly sterically-hindered aryl azides by para-amino substitution

2018 ◽  
Vol 54 (96) ◽  
pp. 13499-13502 ◽  
Author(s):  
Suguru Yoshida ◽  
Junko Tanaka ◽  
Yoshitake Nishiyama ◽  
Yuki Hazama ◽  
Takeshi Matsushita ◽  
...  
Keyword(s):  
Amino Group ◽  
Aryl Azides ◽  
Sterically Hindered

Introduction of an amino group at the para position of doubly sterically-hindered aryl azides significantly enhances their clickability with cyclooctynes.

Effect of lanthanide shift reagents on 1H NMR spectra of aminopyridines

1979 ◽  
Vol 44 (3) ◽  
pp. 908-911 ◽  
Author(s):  
Antonín Lyčka ◽  
Dobroslav Šnobl
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
Electron Donor ◽  
Electron Acceptor ◽  
Nmr Spectra ◽  
Pyridine Ring ◽  
Chemical Shifts ◽  
Amino Group ◽  
H Nmr ◽  
Lanthanide Shift Reagents

The effect of Eu(dpm)3 and Pr(dpm)3 on the proton spectra of 2-amino-, 3-amino- and 4-aminopyridines has been studied by the 1H NMR spectroscopy in tetrachlomethane and deuteriochloroform at 25 °C. Relative changes of the induced chemical shifts of pyridine carrying electron-donor substituents (amino group) are the same as the values given in literature for pyridine ring with electron-acceptor substituents.

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