Nucleophilic substitution of a 4-dimethylamino group in quinoline proton sponges. Stabilization of 4-quinolones in hydroxy form. Synthesis of a proton sponge based on 8-hydroxyquinoline

Reaction of (Z)-4-((dimethylamino)methylene)-1-phenylpyrazolidine-3,5-dione (1) with different nucleophiles is described. Treatment of enaminone 1 with phenylhydrazine led to 3-oxo-N’,2-diphenyl-2,3-dihydro-1H-pyrazole-4-carbohydrazide 7. New enaminone derivatives 2–6 and 12–14 were conveniently obtained in high yields via nucleophilic substitution of the dimethylamino group in enaminone 1 when reacted with o-aminophenol, o-aminothiophenol, ethanolamine, cysteamine hydrochloride, piperidine, morpholine, 2-aminopyridine and glycine. Reaction of enaminone 1 with diaza-nucleophiles, such as hydrazine hydrate, ethylenediamine and o-phenylenediamine, afforded the corresponding bis-enaminones 9–11. Anti-inflammatory and antimicrobial activities of some new products were evaluated. Compounds 1, 2, 4, 7, 12a, and 12b showed high anti- inflammatory activity compared with indomethacin as the reference, while the highest antimicrobial effect was observed in the case of compound 3.

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ChemInform Abstract: New “Proton Sponge” Compounds. Part 5. “Proton Sponges” and the Geometry of Hydrogen Bonds: Aromatic Nitrogen Bases with Exceptional Basicities

ChemInform ◽

10.1002/chin.198842380 ◽

1988 ◽

Vol 19 (42) ◽

Author(s):

H. A. STAAB ◽

T. SAUPE

Keyword(s):

Hydrogen Bonds ◽

Proton Sponge ◽

Nitrogen Bases ◽

Proton Sponges

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Crystal chemistry of tetraradial species. Part 9. The versatile BPh4- anion, or how organoammonium H(N) atoms compete for hydrogen bonding

Canadian Journal of Chemistry ◽

10.1139/v98-077 ◽

1998 ◽

Vol 76 (5) ◽

pp. 583-611 ◽

Cited By ~ 19

Author(s):

Katherine N Robertson ◽

Pradip K Bakshi ◽

Susanne D Lantos ◽

T Stanley Cameron ◽

Osvald Knop

Keyword(s):

Hydrogen Bonding ◽

Crystal Structures ◽

Solvent Molecule ◽

Proton Sponge ◽

Bond Forming ◽

Steric Accessibility ◽

Bicyclic Diamines ◽

Proton Sponges ◽

The Many ◽

Considerable Detail

In organoammonium cations containing two or more N atoms, the H(N) atom introduced by the protonation may engage in an N→H(N)...Y bond to an external acceptor (anion or solvent molecule); in an intra-cation (intra-annular) N→H(N)...N' bond; or in a branched N→H(N)...N',Y bond(s), simultaneously intra-cation and to one or more external acceptors. The outcome of the competition for these bond types is determined by various factors, e.g., the size of the ring to be closed by insertion of the H(N) atom, steric accessibility of H(N), and the H-bond-forming strength of Y. Some of these are discussed in considerable detail and are exemplified by the hitherto unreported crystal structures of the tetraphenylborates (solvated or unsolvated) of the 2,2':6',2"-terpyridinium (1), 2,3-bis(2-pyridyl)pyrazinium (2), 2,2'-dipyridylammonium (3), 6,7-dihydro[b,j][1,10]phenanthrolinium (9), 2,4,7-triamino-6-pteridinium (triamterenium, 10), proton-sponge (1-Me2N-8-Me2NH-naphthalene, 11, 12), and 9-amino-1,2,3,4-tetrahydroacridinium (tacrinium, 13) cations. The crystal structures of the comparison compounds 2,3-bis(2-pyridyl)pyrazine (4) and its mono- (2A) and diprotonated (3) chlorides, and of 2-phenylpyridinium (6) and 7,8-benzoquinolinium (7, 8) tetraphenylborates, have also been determined. The many interesting features of these crystal structures, such as the X→H(X)...phenyl bonding (X = N, O, C), are commented upon and crystallographic comparisons with numerous literature compounds are offered. Included in the discussion are the monoprotonated intrabridgehead cations of the bicyclic diamines of Alder et al., the N-H(N)-N' angle of which has been shown, analytically, to be dominated by the size of the smallest of the rings in these tricyclic systems.Key words: crystal structures, hydrogen bonding, intrabridgehead cations, proton sponges, tetraphenylborates.

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10-Dimethylamino Derivatives of Benzo[h]quinoline and Benzo[h]quinazolines: Fluorescent Proton Sponge Analogues with Opposed peri-NMe2/–N═ Groups. How to Distinguish between Proton Sponges and Pseudo-Proton Sponges

The Journal of Organic Chemistry ◽

10.1021/acs.joc.6b00917 ◽

2016 ◽

Vol 81 (13) ◽

pp. 5574-5587 ◽

Cited By ~ 15

Author(s):

Alexander F. Pozharskii ◽

Valery A. Ozeryanskii ◽

Vladimir Y. Mikshiev ◽

Alexander S. Antonov ◽

Anatoly V. Chernyshev ◽

...

Keyword(s):

Proton Sponge ◽

Proton Sponges ◽

Derivatives Of

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Crystal chemistry of tetraradial species. Part 8. Mix and match: cation geometry, ion packing, hydrogen bonding, and π–π interactions in cis-2,2′-bipyridinium(1+) and 1,10-phenanthrolinium(1+) tetraphenylborates — and what about proton sponges?

Canadian Journal of Chemistry ◽

10.1139/v96-023 ◽

1996 ◽

Vol 74 (2) ◽

pp. 201-220 ◽

Cited By ~ 33

Author(s):

Pradip K. Bakshi ◽

T. Stanley Cameron ◽

Osvald Knop

Keyword(s):

Hydrogen Bonding ◽

Detailed Comparison ◽

Spectroscopic Properties ◽

Stacking Interactions ◽

Proton Sponge ◽

Bonding Interaction ◽

Proton Sponges ◽

In Cis ◽

Considerable Detail ◽

Mix And Match

The crystal structures at −20 °C of cis-2,2′-bipyridinium(1+) (BPTB, P21/n, a = 9.249(3), b = 14.093(7), c = 20.285(3) Å, β = 92.86(2)°, Z = 4) and 1,10-phenanthrolinium(1+) (PTB, P21/c, a = 11.194(2), b = 13.837(3), c = 18.303(3) Å, β = 107.82(1)°, Z = 4) tetraphenylborates have been determined. Inasmuch as 1,10-phenanthroline is an aromatically bridged cis-2,2′-bipyridine, monoprotonation results, in both systems, in the formation of an intra-cation N—H … N′ hydrogen bond, the geometric and spectroscopic properties of which we have investigated. The cation skeleton in PTB is planar to 0.03(2) Å; in BPTB the dihedral angle between the two cation ring planes is 5.2°. In the pale yellow PTB there are significant π–π stacking interactions that persist into solution. The effect of protonation on the geometry of the 2,2′-bipyridine and 1,10-phenanthroline systems is examined in considerable detail and compared with the corresponding effects in the paraquat(2+) and similar cations. On both geometric and spectroscopic (infrared spectra between 10 and 295 K) evidence, the N—H … N′ hydrogen-bonding interaction is stronger in BPTB; in PTB this interaction is among the weakest reported in crystals, the ν(NH) stretching frequency at 10 K being as high as 3279 cm−1. A detailed comparison of the geometries of the intra-cation N—H … N′ bonds in BPTB and PTB with those in classical and modified proton-sponge cations has led to the formulation of criteria useful in predicting the occurrence of proton-sponge-like properties. Key words: bipyridinium ions, hydrogen bonding, phenanthrolinium ions, proton sponges, tetraphenylborates.

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