The Synthesis and Properties of Some Simple 1,4-Dihydropyridines

Kosower, Edward M.; Sorensen, T. S.

doi:10.1021/jo01058a005

Cited by 38 publications

(9 citation statements)

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“…With less contribution from conjugation, the π – π * transition becomes a higher energy transition (S 2 ) and 1,4,5,6‐tetrahydronicotinamides do not absorb above 300 nm . On the other hand, acetyldihydropyridine absorbs at around 350 nm due to similar conjugation as found in dihydronicotinamide . In short, TDDFT computations presented here match the experimental results very well (See Table ), although the computations normally give higher transition energies; the results could be improved with a higher level calculation.…”

Section: Resultssupporting

confidence: 63%

“…When dihydropyridine is twisted away from planar conformation, as in the case of NADH in liver alcohol dehydrogenase (PDB ID: 1HET) , the transition is weakened (smaller oscillator strength). Dihydropyridine without carboxamide group does not have 340‐nm band , The S 1 ( π – π *) transition is found to be at around 280 nm. With less contribution from conjugation, the π – π * transition becomes a higher energy transition (S 2 ) and 1,4,5,6‐tetrahydronicotinamides do not absorb above 300 nm .…”

Section: Resultsmentioning

confidence: 90%

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Mechanistic Analysis of Fluorescence Quenching of Reduced Nicotinamide Adenine Dinucleotide by Oxamate in Lactate Dehydrogenase Ternary Complexes

Peng

Callender

2017

Photochem & Photobiology

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Fluorescence of Reduced Nicotinamide Adenine Dinucleotide (NADH) is extensively employed in studies of oxidoreductases. A substantial amount of static and kinetic work has focused on the binding of pyruvate or substrate mimic oxamate to LDH•NADH where substantial fluorescence quenching is typically observed. However, the quenching mechanism is not well understood limiting structural interpretation. Based on time-dependent density functional theory (TDDFT) computations with cam-B3LYP functional in conjunction with the analysis of previous experimental results, we propose that bound oxamate acts as an electron acceptor in the quenching of fluorescence of NADH in the ternary complex, where a charge transfer (CT) state characterized by excitation from the highest occupied molecular orbital (HOMO) of the nicotinamide moiety of NADH to the lowest unoccupied molecular orbital (LUMO) of oxamate exists close to the locally excited (LE) state involving only the nicotinamide moiety. Efficient quenching in the encounter complex like in pig heart LDH requires that oxamate forms a salt bridge with Arg-171 and hydrogen bonds with His-195, Thr-246 and Asn-140. Further structural rearrangement and loop closure, which also brings about another hydrogen bond between oxamate and Arg-109, will increase the rate of fluorescence quenching as well.

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Section: Resultssupporting

confidence: 63%

Section: Resultsmentioning

confidence: 90%

Mechanistic Analysis of Fluorescence Quenching of Reduced Nicotinamide Adenine Dinucleotide by Oxamate in Lactate Dehydrogenase Ternary Complexes

Peng

Callender

2017

Photochem & Photobiology

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“…Dihydropyridines generally absorb around 270 nm (Kosower and Sorensen, 1962;Cook and Lyons, 1965). The substantial red-shift observed for dihydronicotinamides (-70 nrn, see Table 2) cannot be ' accommodated by the purely inductive effect of a non-conjugated carboxamide moiety.…”

Section: Resultsmentioning

confidence: 98%

Spectroscopic Investigation of Dihydronicotinamides‐i: Conformation, Absorption, and Fluorescence

Fischer

Fleckenstein

Hönes

1988

Photochem & Photobiology

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The 1(N)-(2,6-dichlorobenzyl)-I,4-dihydronicotinamide (I). N-methyl-and N,N-dimethyl-1(N)-(2,6-dichlorobenzyl)-l,4-dihydronicotinamide (I1 and III), respectively). and l(N)-(2,6-dichlorobenzyl)-2-aminomethy1-1,4-dihydronicotinic acid lactame (IV) were synthesized as model compounds for natural coenzymes, and systematically studied by 'H NMR, UViVlS absorption and fluorescence spectroscopy. The absorption at -340 nm argues for an effective conjugation between dihydropyridine and carboxamide 7r-system, and rules out any severely twisted conformation. For the natural coenzymes NADH and NMNH, as well as for I and I1 (with no or only one N-arnide substituent), IH NMR definitively establishes a transoid conformation in solution, with the carbonyl 0 close to 2-H of the dihydropyridine ring. N,N-dimethyl substitution effectively inverts the carboxamide orientation into the cisoid form. The 'H NMR data (as well as molar extinctions) for the fused-ring derivatives IV and V, with a fixed cisoid and transoid structure, respectively, provide final proof for the conformational assignment.Absorption maxima are shifted to lower energies with increasing solvent polarity. In solvents which can act as hydrogen bond acceptors to the carboxamide N-H, absorption shows a general blue-shift of -10 nm. H-bond donor solvents do not affect absorption maxima but enhance molar extinction.Fluorescence maxima show a similar dependence on solvent polarity but no specific hydrogen-bonding effect. Fluorescence quantum yields appear increased tenfold in solvents donating H-bonds to the carboxamide C=O group. These results are interpreted in terms of the vinylogous amide resonance between C = O function and ring-N lone pair being the electronic interaction dominating in the ground state of dihydronicotinamides.

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“…Nominal molecular weights were determined by mass spectrometry; isotopic abundance of P + 1 and P + 2 peaks were as expected. 6 The mass spectrum indicated COS and the ketene as the principal fragments, due at least in large part to thermal cleavage.…”

Section: Experimental Section14mentioning

confidence: 98%

“…Parallel attempts to prepare the bisthio acids (or the intermediate pyridinium salts) from monoalkylmalonyl chlorides also failed. 6 However, reaction of disubstituted malonyl chlorides under similar conditions afforded the bisthio acids la-c as low-melting solids.…”

mentioning

confidence: 99%

Synthesis of 1,2-dithiolane-3,5-diones and thietane-2,4-diones

Schauble¹,

Williams²

1972

J. Org. Chem.

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Notes temperature for 36 hr, an additional 400 ml of methylene chloride was added, and the mixture was washed with -water. Much of the product was insoluble in the organic layer and was collected on a filter (34 g). An additional 18 g of crystalline product was obtained by evaporation of the methylene chloride filtrate. The combined crude product (52 g, 95%) was dried and recrystallized from a mixture of benzene and petroleum ether to give colorless crystals: mp 133-133.5°d ec; nmr (CDC1S) S 2.15 (s, 3, CH3), 3.17-3.73 (m, 8, morpholine ring protons), 7.87 (s, 4, aromatic protons), 10.25 (m, 1, NH).

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The Synthesis and Properties of Some Simple 1,4-Dihydropyridines

Cited by 38 publications

References 2 publications

Mechanistic Analysis of Fluorescence Quenching of Reduced Nicotinamide Adenine Dinucleotide by Oxamate in Lactate Dehydrogenase Ternary Complexes

Mechanistic Analysis of Fluorescence Quenching of Reduced Nicotinamide Adenine Dinucleotide by Oxamate in Lactate Dehydrogenase Ternary Complexes

Spectroscopic Investigation of Dihydronicotinamides‐i: Conformation, Absorption, and Fluorescence

Synthesis of 1,2-dithiolane-3,5-diones and thietane-2,4-diones

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