Photochemistry of Thiazoles, Isothiazoles and 1,2,4‐Thiadiazoles

Pavlik, James W.

doi:10.1002/chin.200415246

Cited by 2 publications

(6 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Examples of the formation of thiazoles through photochemical ring-degenerate rearrangements have been reported [4,6]. However, in many cases, mixtures of photoisomers are obtained through competing mechanisms, and the product distribution depends on the substrate and solvent used.…”

Section: Thiazolesmentioning

confidence: 99%

“…In several cases, however, irradiations have been conducted for mechanistic purposes only, and mixtures of photoisomers arising from competing reaction mechanisms are often formed [4,6].…”

Section: Thiazolesmentioning

confidence: 99%

“…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.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Synthesis of Heteroaromatics via Rearrangement Reactions

Vivona

Buscemi

Pibiri

et al. 2009

Handbook of Synthetic Photochemistry

View full text Add to dashboard Cite

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

show abstract

Section: Thiazolesmentioning

confidence: 99%

“…In several cases, however, irradiations have been conducted for mechanistic purposes only, and mixtures of photoisomers arising from competing reaction mechanisms are often formed [4,6].…”

Section: Thiazolesmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Synthesis of Heteroaromatics via Rearrangement Reactions

Vivona

Buscemi

Pibiri

et al. 2009

Handbook of Synthetic Photochemistry

View full text Add to dashboard Cite

show abstract

“…The photoisomerization of pentatomic heterocyclic compounds is one of the most studied photochemical reaction allowing to obtain some significant synthetic processes [1][2][3]. Some years ago, the photochemical isomerization of 1,2,4-oxadiazole derivatives 1 has been reported to give the corresponding triazoles 2 (Scheme 1) [4].…”

Section: Introductionmentioning

confidence: 99%

Hydrogen atom transfer in the photochemical isomerization of hydrazones of 1,2,4-oxadiazole derivatives

D’Auria

2021

Photochem Photobiol Sci

View full text Add to dashboard Cite

DFT calculations on the photoisomerization of hydrazones of 1,2,4-oxadiazole derivatives to 1,2,5-triazoles have been performed showing that the reaction occurred through the first excited singlet state. The Z isomer gave the reaction through a hydrogen atom transfer of the hydrazonic nitrogen atom to the nitrogen atom in four position on the oxadiazole ring. In this case, the isomerization was a concerted reaction. The E isomer could undergo the same reaction. However, it could not be a concerted reaction but required the presence of a ring opening intermediate.

show abstract

Photochemistry of Thiazoles, Isothiazoles and 1,2,4‐Thiadiazoles

Abstract: For Abstract see ChemInform Abstract in Full Text.

Cited by 2 publications

References 16 publications

Synthesis of Heteroaromatics via Rearrangement Reactions

Synthesis of Heteroaromatics via Rearrangement Reactions

Hydrogen atom transfer in the photochemical isomerization of hydrazones of 1,2,4-oxadiazole derivatives

Contact Info

Product

Resources

About