Die bildung von thiirenen

Timm, U.; Buhl, H.; Meier, Herbert

doi:10.1002/jhet.5570150440

Cited by 27 publications

(15 citation statements)

References 16 publications

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“…The position of a 13 C label was completely retained in Wolff rearrangements of 780d [542] and 780i. [551] In contrast, 780e reacted with partial (photolysis) to almost complete (thermolysis) 1,2-shift of sulfur. [542b] Conjugation of phenyl with the carbenic site stabilizes 784, hence rearrangement proceeds from 790d to 784d (790f to 784f) but not in the reverse direction.…”

Section: -Thiadiazoles and Related Substratesmentioning

confidence: 99%

100 Years of the Wolff Rearrangement

2002

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The conversion of α‐diazo ketones into ketenes, and products derived therefrom, was discovered by Wolff in 1902. Major applications of the Wolff rearrangement, such as the Arndt−Eistert reaction (homologation of carboxylic acids) and the ring contraction of cyclic ketones, have been with us for some while. Nevertheless, substantial progress has been made recently. The reaction mechanism has been explored by means of matrix isolation, time‐resolved spectroscopy, and computation. Full retention of configuration of the migrating group has been established by using enantioselective chromatography. The Arndt−Eistert reaction has witnessed a renaissance in the field of natural products, in particular β‐amino acids and β‐peptides. Ring‐contracting Wolff rearrangements and ketene cycloadditions have been applied in syntheses of increasingly complex, biologically active target molecules. These accomplishments, as well as unsolved problems, are addressed in the present review. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

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Section: -Thiadiazoles and Related Substratesmentioning

confidence: 99%

100 Years of the Wolff Rearrangement

2002

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“…As one can see FC-2 in Figure 3, this vertical excitation energy is computed to be 104 kcal/mol, which is in good accordance with the experimental findings (235–280 nm = 122–102 kcal/mol). 24−32…”

Section: Resultsmentioning

confidence: 99%

“…This assumption is based on a recent paper. 70 Nevertheless, according to the available experimental reports, [24][25][26][27][28][29][30][31][32]68,69 no species on the triplet state have been observed so far. Therefore, the photochemical reactions studied in this work are all focused on the singlet surfaces.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Investigations on the Photoisomerization Reactions of Five-Membered Ring Heterocyclic Molecules Containing Sulfur and Selenium Atoms

2018

ACS Omega

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The restricted active space self-consistent field method in the 26-electron/27-orbital active space and the 6-311(d) basis set has been used to investigate the mechanisms of the photochemical isomerization reactions concerning the model systems of 1,2,3-thiadiazole and 1,2,3-selenadiazole. The computational works suggest that the preferred reaction paths for both 1,2,3-thiadiazole and 1,2,3-selenadiazole are as follows: reactant → Franck–Condon region → conical intersection → intermediate → transition states → photoproducts. As a result, the structures of the conical intersections, which play a decisive role in these photoisomerization reactions, are obtained. In particular, the present theoretical evidences demonstrate that the potential energy surfaces for the formation of 1,3-diradicals are quite flat. This may explain why their experimental detections are so difficult.

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“…Scheme 1 gives a survey of the formation of these heterocycles from four-to seven-membered rings. [2][3][4][5][6][7][8][9][10][11][12] (The examples given in refs. 2-12 are typically early established reaction examples.)…”

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confidence: 99%

“…Its nitrogen and sulfur content corresponded largely to intact 1,2,3-thiadiazole rings and a complete alkylation of all phenolic OH groups. The photocrosslinking of the polymers 1c¢ and 1i¢ could be per-Scheme 1 Formation of S-heterocycles by ring cleavage of 1,2,3thiadiazoles 1: 2,4-dialkylidene-1,3-dithietanes 6, 2 3,5-dialkylidene-1,2,4-trithiolanes 7, 3,4 3,6-dialkylidene-1,2,4,5-tetrathianes 8, 3 2-alkylidene-1,3-dithioles 9, 5-10 thiophenes 10, 3,6,7,9,11,12 1,4-dithiines 11, 5,6,7,9 formed in solution (benzene or dichloromethane) or in thin neat films, which were spin-coated or produced by evaporation of saturated solutions. The absorption maxima of 1c¢ and 1i¢ occur at 260 nm; additionally to this p→p* transitions, n→p* transitions appear in the form of an extended shoulder at about 310 nm (CH 2 Cl 2 ).…”

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confidence: 99%

1,2,3-Thiadiazoles with Unsaturated Side Chains; Synthesis, Polymerization, and Photocrosslinking

Al-Smadi¹,

Hanold²,

Kalbitz³

et al. 2009

Synthesis

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1,2,3-Thiadiazoles with polymerizable functionalities in the 4-position were synthesized as potential negative photoresists. The polymerization to soluble, film-forming materials must leave the heterocyclic rings intact, because they are needed for photocrosslinking reactions to give insoluble materials. 1,2,3-Thiadiazoles 1 cycloeliminate N 2 on irradiation. The resulting 1,3-diradicals 2 have various options for stabilization processes leading to alkynes 3 or to higher heterocycles 5-12. The generation of atomic sulfur and its involvement in these subsequent reactions must be avoided. Therefore, systems like model compound 1a, in which the 1,3diradicals form 2-methylene-1,3-dithioles (dithiafulvenes) 9 were selected here. Optimization gave ultimately two materials for application as photoresists. Monomer 1c could be polymerized in the presence of boron trifluoride to soluble 1c¢, which on irradiation formed 1c¢¢ as a cross-linked insoluble polymer. Furthermore, thiadiazole 1f was attached to polystyrene 26. The resulting soluble polymer 1i¢ yielded the insoluble material 1i¢¢ on irradiation.

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Die bildung von thiirenen

Cited by 27 publications

References 16 publications

100 Years of the Wolff Rearrangement

100 Years of the Wolff Rearrangement

Mechanistic Investigations on the Photoisomerization Reactions of Five-Membered Ring Heterocyclic Molecules Containing Sulfur and Selenium Atoms

1,2,3-Thiadiazoles with Unsaturated Side Chains; Synthesis, Polymerization, and Photocrosslinking

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