Synthesis of dyes containing fluorine atoms in the polymethine chain

Krasnaya, Zh. A.; Stytsenko, T. S.; Bogdanov, V. S.; Monich, N. V.; Kul'chitskii, M. M.; Pazenok, S. V.; Yagupol’skii, L. M.

doi:10.1007/bf00958049

Cited by 4 publications

(4 citation statements)

References 2 publications

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“…We verified that the protio-, phenyl-, chloro-, fluoro-, and dienones 7a − d did not undergo cyclization in refluxing THF. The cyano - substituted dienone 7e is also reported to be stable, and we reasoned that the unexpected reactivity of nitro-substituted dienone 7g was due to the ability of the nitro group to stabilize a developing negative charge in the transition state in the formation of a cyclohexadiene intermediate.…”

Section: Resultssupporting

confidence: 56%

Demonstrating the Synergy of Synthetic, Mechanistic, and Computational Studies in a Regioselective Aniline Synthesis

Davies

Marcoux²,

Kuethe³

et al. 2004

J. Org. Chem.

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Tri- and tetrasubstituted anilines are formed in good to excellent yields by the addition of ketones to vinamidinium salts (up to 98%). The reaction proceeds via the formation of dienone intermediates, which react to form an enamine with the liberated amine. In the case of a nitro, or dimethylaminomethylene substituent, the enamines undergo a facile electrocyclic ring closure to form a cyclohexadiene, which goes on to form anilines with a high degree of selectivity (up to 50:1) with a minor competing pathway proceeding via the enol providing phenols. Competition experiments using isotopic substitution reveal that the rate determining step en route to dienone is enol/enolate addition to the vinamidinium salt, which is characterized by an inverse secondary isotope effect (k(H/D) 0.7-0.9). Computational studies have been used to provide a framework for understanding the reaction pathway. The original proposal for a [1,5]-H shift was ruled out on the basis of the calculations, which did not locate a thermally accessible transition state. The minimum energy conformation of the enamine is such that a facile electrocyclic ring closure is ensured, which is corroborated by the experimental studies. A framework for understanding the reaction pathway is presented.

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Section: Resultssupporting

confidence: 56%

Demonstrating the Synergy of Synthetic, Mechanistic, and Computational Studies in a Regioselective Aniline Synthesis

Davies

Marcoux²,

Kuethe³

et al. 2004

J. Org. Chem.

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“…A. Krasnaya (Moscow). The synthesis of A1TC and A2TA is described in ref , and that of S3 in ref . The resonant dyes S1 and S2 have been synthesized similarly to the latter.…”

Section: Methodsmentioning

confidence: 99%

Exciton-Like and Charge-Transfer States in Cyanine−Oxonol Ion Pairs. An Experimental and Theoretical Study

Baraldi¹,

Momicchioli²,

Ponterini³

et al. 2001

J. Phys. Chem. A

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Absorption and fluorescence emission properties of cyanine−oxonol mixed dyes, i.e., salts formed by a cationic cyanine with an anionic oxonol as counterion, were investigated both theoretically and experimentally in order to probe the effects of ion pairing occurring in low-polarity solvents. We analyzed, in particular, three model systems (S1, S2, and S3) built combining thiacarbo- and thiadicarbocyanine (C1, C2) with two vinylogous oxonol chromophores (A1/A1F, A2). In systems S1 (C1−A1) and S2 (C2−A2), where the visible absorption bands of the individual ions are almost superimposed, the formation of ion pairs gives rise to marked spectral alterations traceable to interchromophore resonance interactions. On the contrary, in system S3 (C2−A1F), whose components absorb widely apart, the spectrum of the contact ion pair and that of the dissociated form differ only for the relative band intensities. In both cases, however, contact ion pairing results in complete quenching of the emission of the chromophoric units. Such behaviors, emphasized by absorption and fluorescence emission and excitation spectra of both the mixed dyes and their components in solvents of different polarities, were the subject of a theoretical study based in particular on the calculation of structures and electronic spectra of the contact ion pairs. Molecular dynamics (MD) simulations and local full geometry optimizations led to two types of structures characterized by almost parallel and orthogonal arrangements of the long molecular axes. CS INDO SCI calculations using both arrangements emphasized the role of the exciton coupling between the local HOMO−LUMO excitations of the two chromophoric units. The most striking spectral characteristics in low-polarity solvent turned out to be explainable in terms of parallel type arrangements, even if an appreciable contribution of the orthogonal type structure was to be invoked for a complete interpretation of the S1 spectral properties. In all contact ion pairs, independently of the structure, the lowest excited singlet is a forbidden anion → cation charge transfer (CT) state explaining why no fluorescence emission was observed in such systems.

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“…Vinamidinium salts react with methylacetoacetate to form dienones. In the case of protio-, 1 phenyl-, 2 chloro-, 3 fluoro-, 4 and cyano-substituted 5 dienones they do not undergo subsequent spontaneous downstream chemistry. However, we have demonstrated that ring closure to provide aromatic products occurs in the case of nitro-, phenylsulfonyl-, and dimethylaminomethylene substitution.…”

Section: Introductionmentioning

confidence: 98%

“…Vinamidinium salts react with methylacetoacetate to form dienones. In the case of protio-, phenyl-, chloro-, fluoro-, and cyano-substituted dienones they do not undergo subsequent spontaneous downstream chemistry. However, we have demonstrated that ring closure to provide aromatic products occurs in the case of nitro-, phenylsulfonyl-, and dimethylaminomethylene substitution. , The major reaction pathway has been formalized as (1) enamine or enol formation, (2) electrocyclization, and (3) elimination of dimethylamine to provide the aromatic product (Scheme ) .…”

Section: Introductionmentioning

confidence: 99%

Computational Studies on the Electrocyclizations of 1-Amino-1,3,5-hexatrienes

2004

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Electrocyclizations of 1,3,5-hexatrienes containing up to four electron-donating and/or electron withdrawing substituents have been studied computationally using the hybrid density functional, B3LYP. Electron donating substituents at positions C-1 and C-5 decrease activation barriers by 0.3 to 2.3 kcal/mol. Introducing of an electron-withdrawing group, CO(2)Me, at C-4 further decreases the activation energy by 7 kcal/mol. Electron-withdrawing groups (NO(2), SO(2)Ph and C=N(+)Me(2)) at C-2 have a profound effect of 17-25 kcal/mol on the activation energy.

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Synthesis of dyes containing fluorine atoms in the polymethine chain

Cited by 4 publications

References 2 publications

Demonstrating the Synergy of Synthetic, Mechanistic, and Computational Studies in a Regioselective Aniline Synthesis

Demonstrating the Synergy of Synthetic, Mechanistic, and Computational Studies in a Regioselective Aniline Synthesis

Exciton-Like and Charge-Transfer States in Cyanine−Oxonol Ion Pairs. An Experimental and Theoretical Study

Computational Studies on the Electrocyclizations of 1-Amino-1,3,5-hexatrienes

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