Photochemistry of 4- and 5- phenyl substituted isoxazoles

Pavlik, James W.; Martin, Heather St.; Lambert, Karen A.; Lowell, Jennifer A.; Tsefrikas, Vikki M.; Eddins, Cheryl K.; Kebede, Naod

doi:10.1002/jhet.5570420215

Cited by 27 publications

(18 citation statements)

References 40 publications

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“…In a computational study, it has been shown that bicyclic intermediates are involved (compare 6–8 in Scheme ) . More generally in such reactions, a competition between this mechanism and mechanisms involving homolytic or heterolytic fragmentation of the bond between the two heteroatoms is discussed …”

Section: Photochemical Heteroatom Isomerization Of Heterocyclic Compomentioning

confidence: 99%

Photochemical Rearrangements in Heterocyclic Chemistry

2019

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Heterocyclic compounds play an important role in many domains of chemistry. They are important structural elements in bioactive compounds. Photochemical reactions enable transformations of such compounds in a very convenient way. In many cases no chemical reagent is used. Members of one compound family can be transformed into members of another one. Three important types of photochemical rearrangements with heterocyclic compounds are discussed: Photochemical heteroatom isomerization involving heteroatoms and substituents, photochemical reactions involving hydrogen atom transfer (HAT) and photochemical electrocyclization.

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Section: Photochemical Heteroatom Isomerization Of Heterocyclic Compomentioning

confidence: 99%

Photochemical Rearrangements in Heterocyclic Chemistry

2019

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“…23,24 istražuje izomerizacije izoksazola i benzizoksazola pomoću CASSCF i MP2-CAS računskih metoda. Stariji mehanizam 22,25,26 za te reakcije bio mehanizam je ciklizacije-izomerizacije (shema 3) koji uključuje prvotno nastajanje bicikličkog međuprodukta nakon kojeg slijedi [1,3]-pomak dušika u sekundarni biciklički međuprodukt koji podliježe otvaranju azirinskog prstena u produkte fototranspozicije (P 1 -P 3 ). Ti međuprodukti nisu nikad zamijećeni, te je autor predložio drugi, izravni mehanizam preko stožastog presjeka (CI).…”

Section: Pavlik I Surunclassified

Reakcije oksazola i njihovih derivata u pobuđenom stanju. I. dio: Fototranspozicije u prstenu

Šagud

Šindler‐Kulyk

2018

Kem. Ind.

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Heterocyclic compounds are a very important part of organic chemistry. Oxazole is a five-membered heterocycle with nitrogen and oxygen atoms in the ring. Oxazole is part of complex structures used in medicinal chemistry, pharmacology, and material chemistry. In the excited state, the oxazole ring can rearrange itself via several reaction mechanisms. In this paper, an extensive literature overview is given for photoisomerisations (phototranspositions) in oxazole, isoxazole, and benzisoxazole ring. A literature review is also given for phototransformations of the ring in the presence of oxygen (photooxygenation reactions), as well as for photoformation of the oxazole ring.

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“…Representative examples include: (i) the synthesis of 2-trifluoromethyloxazole 77 from a preparative-scale irradiation at 254 nm in acetonitrile of the easily accessible 3-trifluoromethylisoxazole 76 [51]; and The isoxazole-to-oxazole rearrangement has been also used in the synthesis of benzocondensed derivatives. The irradiation of benzisoxazoles 81 in water (highpressure Hg lamp) produces almost quantitative yields of the corresponding benzoxazoles 82 (Scheme 12.24) [53].…”

Section: Oxazolesmentioning

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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Photochemistry of 4- and 5- phenyl substituted isoxazoles

Cited by 27 publications

References 40 publications

Photochemical Rearrangements in Heterocyclic Chemistry

Photochemical Rearrangements in Heterocyclic Chemistry

Reakcije oksazola i njihovih derivata u pobuđenom stanju. I. dio: Fototranspozicije u prstenu

Synthesis of Heteroaromatics via Rearrangement Reactions

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