1,2-Dithiines and precursors, XVI: Synthesis, structure, and reactivity of non-anellated 1,2-dithiines

Schroth, Werner; Dunger, S.; Billig, F.; Spitzner, R.; Herzschuh, Rainer; Vogt, Almut; Jende, T.; Israel, G.; Barche, J.; Ströhl, Dieter; Sieler, Joachim

doi:10.1016/0040-4020(96)00752-1

Cited by 37 publications

(21 citation statements)

References 78 publications

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“…The reactions with TCNE and Pd catalysts were carried out under an inert atmosphere by applying a positive pressure of Ar. Compounds 2, [7] 10, [7] 11, [7] 22, [30] 23, [31] 26, [32] 31, [33] 32, [32] 35, [34] 36, [35] 37, [36] 38, [37] and 4-ethynyl-N,N-dihexylaniline [38] were prepared according to literature procedures. Column chromatography (CC) and plug filtrations were carried out with Fluka SiO 2 60 (particle size 40-63 mm, 230-400 mesh) or Fluka Al 2 O 3 (particle size 50-150 mm) and distilled technical solvents.…”

Section: Methodsmentioning

confidence: 99%

Donor‐Substituted 1,1,4,4‐Tetracyanobutadienes (TCBDs): New Chromophores with Efficient Intramolecular Charge‐Transfer Interactions by Atom‐Economic Synthesis

Michinobu

Boudon²,

Gisselbrecht³

et al. 2006

Chemistry A European J

267

228

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A wide variety of monomeric and oligomeric, donor-substituted 1,1,4,4-tetracyanobutadienes (TCBDs) have been synthesized by [2+2] cycloaddition between tetracyanoethylene (TNCE) and donor-substituted alkynes, followed by electrocyclic ring opening of the initially formed cyclobutenes. Reaction yields are often nearly quantitative but can be affected by the electron-donating power and steric demands of the alkyne substituents. The intramolecular charge-transfer (CT) interactions between the donor and TCBD acceptor moieties were comprehensively investigated by X-ray crystallography, electrochemistry, UV-visible spectroscopy, and theoretical calculations. Despite the nonplanarity of the new chromophores, which have a substantial twist between the two dicyanovinyl planes, efficient intramolecular CT interactions are observed, and the crystal structures demonstrate a high quinoid character in strong donor substituents, such as N,N-dimethylanilino (DMA) rings. The maxima of the CT bands shift bathochromically upon reduction of the amount of conjugative coupling between strong donor and acceptor moieties. Each TCBD moiety undergoes two reversible, one-electron reduction steps. Thus, a tri-TCBD derivative with a 1,3,5-trisubstituted benzene core shows six reversible reduction steps within an exceptionally narrow potential range of 1.0 V. The first reduction potential E(red,1) is strongly influenced by the donor substitution: introduction of more donor moieties causes an increasingly twisted TCBD structure, a fact that results in the elevation of the LUMO level and, consequently, a more difficult first reduction. The potentials are also strongly influenced by the nature of the donor residues and the extent of donor-acceptor coupling. A careful comparison of electrochemical data and the correlation with UV-visible spectra made it possible to estimate unknown physical parameters such as the E(red,1) of unsubstituted TCBD (-0.31 V vs Fc+/Fc) as well as the maxima of highly broadened CT bands. Donor-substituted TCBDs are stable molecules and can be sublimed without decomposition. With their high third-order optical nonlinearities, as revealed in preliminary measurements, they should become interesting chromophores for ultra-thin film formation by vapor deposition techniques and have applications in opto-electronic devices.

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Section: Methodsmentioning

confidence: 99%

Donor‐Substituted 1,1,4,4‐Tetracyanobutadienes (TCBDs): New Chromophores with Efficient Intramolecular Charge‐Transfer Interactions by Atom‐Economic Synthesis

Michinobu

Boudon²,

Gisselbrecht³

et al. 2006

Chemistry A European J

267

228

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“…It is virtually identical with the dihedral angle found for the saturated 1,2-dithiane-3,6-dicarboxylic acid (60.0°)[241. The S-S torsional angles of 13 (54.6") and 14 (52.6") are a little smaller [22], and the four di-annellated dithiins show values from 47" to 60.7". The recently published microwave structure of 1,2-dithiin (Il), the parent, records 53.9" for the C-S-S-C dihedral an- Figure 1.…”

Section: R 10mentioning

confidence: 96%

An Unorthodox Pathway to the 1,2‐Dithiin System

et al. 1997

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Tetracyanoethylene combines with two molecules of thiobenzophenone in refluxing benzene to give the tetrasubstituted 1,2-dithiin 8 ( 2 1~2 9 % ) besides the corresponding thiophene derivative 9 (40-52%). The X-ray analysis of the ruby-red 8 reveals a half-chair conformation with a torsion angle of 58.9" at the disulfide bond. The thermal desulfurization 8 -+ 9 (benzonitrile, 100°C) proceeds with flI2 = 26.7 h, whereas the sulfur loss induced by triethyl phosphite is a billion times faster. The mechanisms of the formation of 8 and its sulfur extrusion are discussed in the light of recent literature.

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“…Other examples involve naturally occurring thiarubrines 35b [30], as well as variously substituted synthetic derivatives [31]. This photochemical reactivity has been generalized with an application in the synthesis of selenophene 40 obtained in almost quantitative yield from 39 [32].…”

Section: Thiophenesmentioning

confidence: 99%

Synthesis of Heteroaromatics via Rearrangement Reactions

Vivona

Buscemi

Pibiri

et al. 2009

Handbook of Synthetic Photochemistry

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The varied family of heteroaromatics contains a large fraction of organic compounds, many of which have found important applications in different fields. Many synthetic methodologies have been developed to obtain target systems and, among them, photochemical methods represent valid and elegant alternatives when the final targets are difficult to obtain through ground-state chemistry. In this chapter, we describe the photochemical synthesis of heteroaromatic compounds through rearrangement reactions, particularly via ring-transformations of heterocyclic precursors [1][2][3][4][5][6][7].A classification of all photoinduced heterocyclic ring-transformation reactions is quite difficult to achieve due to the large variety of mechanistic pathways, experimental conditions and affecting parameters. In some cases, the photochemical product and the starting substrate have the same heterocyclic nucleus. In this chapter, we will refer to such reactions, characterized by the identity of the starting and final ring, as ring-degenerate rearrangements.In general, photoinduced rearrangements of heterocycles leading to heteroaromatic compounds may involve ring-contraction, internal cyclization, ring-expansion, ring-opening or ring-closure, and ring-fragmentation processes. As for five-membered rings, two processes will be repeatedly quoted throughout this chapter:. The ring contraction-ring expansion route (RCRE), which explains the formal interchange between two adjacent ring-atoms. This results from the photoinduced cleavage of the weakest bond in the ring with formation of a three-membered ring intermediate. The latter is then converted, either thermally or photochemically, into the final five-membered heterocyclic product (see e.g., Scheme 12.22). . The internal cyclization-isomerization route (ICI), which involves the formation of a bicyclic species featuring a single bond between the ring-atoms in the 2-and 5-positions of the original heterocycle. Sigmatropic shifts then occur, leading to different bicyclic intermediates from which the final products will arise (see e.g., Scheme 12.2).Handbook of Synthetic Photochemistry. Edited

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1,2-Dithiines and precursors, XVI: Synthesis, structure, and reactivity of non-anellated 1,2-dithiines

Cited by 37 publications

References 78 publications

Donor‐Substituted 1,1,4,4‐Tetracyanobutadienes (TCBDs): New Chromophores with Efficient Intramolecular Charge‐Transfer Interactions by Atom‐Economic Synthesis

Donor‐Substituted 1,1,4,4‐Tetracyanobutadienes (TCBDs): New Chromophores with Efficient Intramolecular Charge‐Transfer Interactions by Atom‐Economic Synthesis

An Unorthodox Pathway to the 1,2‐Dithiin System

Synthesis of Heteroaromatics via Rearrangement Reactions

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