Photochemistry of the carbon–nitrogen double bond. Part 1. Carbon–nitrogen vs. carbon–carbon double bond isomerisation in the photochemistry of α,β-unsaturated oxime ethers: the benzylideneacetone oxime O-methyl ether system

Pratt, Albert C.; Abdul-Majid, Qais

doi:10.1039/p19860001691

Cited by 14 publications

(2 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast, Omethyloximes 1j and 1k underwent only competing geometrical isomerisation at the carbon-carbon and carbon-nitrogen double bonds on direct and triplet sensitised excitation resulting, in both cases, in a photostationary state comprising the four possible geometrical isomers, but without accompanying cyclisation. 7,8 Prerequisites for photocyclisation are (a) a Z-configuration at the a,b-double bond, achieved by initial geometrical photoisomerisation, and (b) significant contribution from conformers with an s-cis orientation at the R 1 C-CR 2 single bond. Systems with this bond within a ring are forced to adopt an s-cis conformation.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Quinoline synthesis: scope and regiochemistry of photocyclisation of substituted benzylidenecyclopentanone O-alkyl and O-acetyloximes

et al. 2007

Self Cite

View full text Add to dashboard Cite

[DO NOT ALTER/DELETE THIS TEXT]Irradiation of substituted 2-benzylidenecyclopentanone O-alkyl and O-acetyloximes in methanol provides a convenient synthesis of alkyl, alkoxy, hydroxy, acetoxy, amino, dimethylamino and benzo substituted annulated quinolines. paraSubstituents yield 6-substituted-2,3-dihydro-1H-cyclopenta[b]quinolines with 8-substituted products being obtained from ortho-substituted starting materials. Reactions of meta-substituted precursors are highly regioselective, with alkyl substituents leading to 5-substituted 2,3-dihydro-1H-cyclopenta [b]quinolines and more strongly electron-donating substituents generally resulting in 7-substituted products. 2-Furylmethylene and 2-thienylmethylene analogues yield annulated furo-and thieno-[2,3e]pyridines respectively. Sequential E-to Z-benzylidene group isomerisation and six π-electron cyclisation steps result in formation of a short-lived dihydroquinoline intermediate which spontaneously aromatises by elimination of an alcohol or acetic acid. For 2-benzylidenecyclopentanone Oallyloxime, singlet excited states are involved in both steps.

show abstract

Section: Introductionmentioning

confidence: 99%

“…7,8 Prerequisites for photocyclisation are (a) a Z-configuration at the α,β-double bond, achieved by initial geometrical photoisomerisation, and (b) significant contribution from 30 conformers with an s-cis orientation at the R 1 C-CR 2 single bond. Systems with this bond within a ring are forced to adopt an s-cis conformation.…”

Section: Introductionmentioning

confidence: 99%

Quinoline synthesis: scope and regiochemistry of photocyclisation of substituted benzylidenecyclopentanone O-alkyl and O-acetyloximes

et al. 2007

Self Cite

View full text Add to dashboard Cite

show abstract

Photochemistry of Amines and Amino Compounds

Chow

2009

Patai's Chemistry of Functional Groups

View full text Add to dashboard Cite

show abstract

Light‐Induced Chemistry of Oximes and Derivatives

Roth¹

2010

Patai's Chemistry of Functional Groups

View full text Add to dashboard Cite

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.

show abstract

Photochemistry of the carbon–nitrogen double bond. Part 1. Carbon–nitrogen vs. carbon–carbon double bond isomerisation in the photochemistry of α,β-unsaturated oxime ethers: the benzylideneacetone oxime O-methyl ether system

Cited by 14 publications

References 3 publications

Quinoline synthesis: scope and regiochemistry of photocyclisation of substituted benzylidenecyclopentanone O-alkyl and O-acetyloximes

Quinoline synthesis: scope and regiochemistry of photocyclisation of substituted benzylidenecyclopentanone O-alkyl and O-acetyloximes

Photochemistry of Amines and Amino Compounds

Light‐Induced Chemistry of Oximes and Derivatives

Contact Info

Product

Resources

About