SET induced cyclizations of β,γ-unsaturated oximes. A novel photochemical route to dihydroisoxazole derivatives

Horspool, W. M.; Hynd, George W.; Ixkes, Ulrich

doi:10.1016/s0040-4039(99)01759-1

Cited by 7 publications

(2 citation statements)

References 13 publications

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“…This was isolated by conventional column chromatography (toluene/ethyl acetate 7:1). The isolated product exhibited 1 H NMR signals as singlets at δ 7.00 for an oximino hydrogen and at δ 2.65 for a methylene group. These resonances justify the assignment of the structure of the new product as the dihydrooxazine 3a.…”

Section: Resultsmentioning

confidence: 99%

“…Our own recent studies have recorded 1 the photochemical cyclisation of such oximes under SET conditions using DCA and also a novel oxidative intramolecular cyclisation to yield peri-naphthisoxazoles. 2 However, the definitive earlier work by Armesto and his coworkers 3 demonstrated the usefulness of the photochemical reactions of such species in the discovery and subsequent study and development of the aza-di-π-methane rearrangement.…”

Section: Introductionmentioning

confidence: 99%

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Thermal and photochemical reactivity of β,γ-unsaturated oximes in the presence of SnCl4

Horspool¹,

Hynd²,

Ixkes³

2002

Arkivoc

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The thermal reaction of some symmetrically substituted β,γ-unsaturated oximes 2a-d in the presence of one equivalent of tin tetrachloride in toluene leads to the formation of 5,6-dihydro-4H-1,2-oxazines 3a-d. The photochemical reaction follows a different path and yields 5-(diarylhydroxymethyl)-4,4-dimethyl-4,5-dihydroisoxazoles 6a, b. A cationic mechanism is proposed for the thermal cyclisation while the photochemical process is thought to involve an SET process.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermal and photochemical reactivity of β,γ-unsaturated oximes in the presence of SnCl4

Horspool¹,

Hynd²,

Ixkes³

2002

Arkivoc

Self Cite

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Synthesis of Heterocycles from Oximes

Абеле

Lukevics

2010

Patai's Chemistry of Functional Groups

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Light‐Induced Chemistry of Oximes and Derivatives

Roth¹

2010

Patai's Chemistry of Functional Groups

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Photoreactions of oximes have been known for 120 years. The earliest recognized reaction was geometric isomerization, which is still the most prominent oxime photoreaction; it proceeds via a ππ* triplet state. More than sixty years later the intriguing photo‐Beckmann rearrangement came to light, a C–C=N–O to O=C–N–C conversion, generating, for example, ɛ‐caprolactam from cyclohexanone ξιμɛ. The rearrangement proceeds via a ππ* singlet state forming an oxazirane intermediate; the oxazirane ring usually opens in stereospecific fashion. Detailed insight into the stereo‐ and regiochemistry of the rearrangement was gained from steroidal oximes, the most thoroughly investigated class of oximes. Additional photoreactions of oximes or of their ethers and esters include: net loss of hydroxylamine generating carbonyl compounds; loss of water from aldoximes forming nitriles; conversion of ketoximes to nitriles by more complex mechanisms; photochemical O–H cleavage generating iminoxyl radicals, an interesting family of free radicals; N–O cleavage giving rise to iminyl radials, which undergo radical cyclizations. β,γ‐Unsaturated oximes undergo aza‐di‐π‐methane rearrangements, cyclize to oxazolines, and undergo further reorganizations. The palette of oxime reactions has been further enriched by triplet energy transfer or electron transfer sensitization; oximes serve as electron donors or acceptors.

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SET induced cyclizations of β,γ-unsaturated oximes. A novel photochemical route to dihydroisoxazole derivatives

Cited by 7 publications

References 13 publications

Thermal and photochemical reactivity of β,γ-unsaturated oximes in the presence of SnCl4

Thermal and photochemical reactivity of β,γ-unsaturated oximes in the presence of SnCl4

Synthesis of Heterocycles from Oximes

Light‐Induced Chemistry of Oximes and Derivatives

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