Photoinduced molecular transformations. Part 134. Photoinduced stereospecific addition of methanol to 5β-cholest-1-en-3-one oxime and photoinduced deconjugation of its 1-methyl derivative involving stereospecific proton transfer

Suginome, Hiroshi; Nagaoka, Atsushi; Senboku, Hisanori

doi:10.1039/p19920003103

Cited by 6 publications

(1 citation statement)

References 22 publications

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“…On the other hand, the 1-methyl analogue (122) provides 1-methylene (E)-and (Z)-oximes (124) In 62% yield. 96 The photolysis of the a-azido ketone (125) by thermolysis in dimethylaniline. 97 Irradiation of the hypoiodite of 3~-hydroxycholest-5-en-7one (132), prepared in situ with mercury(1r) oxide and iodine in benzene, gives the secosteroid (1 33) and the A-norsteroid (1 34) in 40 and 8 YO yield, respectively.…”

Section: Photochemical Reactionsmentioning

confidence: 99%

Steroids: reactions and partial syntheses

Černý¹

1994

Nat. Prod. Rep.

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Section: Photochemical Reactionsmentioning

confidence: 99%

Steroids: reactions and partial syntheses

Černý¹

1994

Nat. Prod. Rep.

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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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ChemInform Abstract: Photoinduced Molecular Transformations. Part 134. Photoinduced Stereospecific Addition of Methanol to 5β‐Cholest‐1‐en‐3‐one Oxime and Photoinduced Deconjugation of Its 1‐Methyl Derivative Involving Stereospecific Proton Transfer.

1993

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Photoinduced Molecular Transformations. Part 134. Photoinduced Stereospecific Addition of Methanol to 5β-Cholest-1-en-3-one Oxime and Photoinduced Deconjugation of Its 1-Methyl Derivative Involving Stereospecific Proton Transfer.-Photolysis of 5β-cholest-1-en-3-one oxime (I) in MeOH affords products arising from a stereospecific photoaddition of MeOH and new skeletal rearrangement of the photogenerated parent ketone. However, no isoxazole derivative, which is formed in the photolysis of the 5. alpha.-isomer, is detected. On the other hand, irradiation of the 1-methyl derivative (VI) in MeOH results in a photoisomerization in analogy to its 5α isomer giving the β,γ-unsaturated isomer (VII). Labeling studies indicate that the principal reaction of steroidal 1-en-3-one oximes upon irradiation in MeOH is a stereospecific addition of MeOH or a proton to the photogenerated, twisted ground-state double bond of the oxime from the rear side of the steroidal framework. -(SUGINOME, H.; NAGAOKA, A.; SENBOKU, H.; J. Chem.

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Photoinduced molecular transformations. Part 134. Photoinduced stereospecific addition of methanol to 5β-cholest-1-en-3-one oxime and photoinduced deconjugation of its 1-methyl derivative involving stereospecific proton transfer

Cited by 6 publications

References 22 publications

Steroids: reactions and partial syntheses

Steroids: reactions and partial syntheses

Light‐Induced Chemistry of Oximes and Derivatives

ChemInform Abstract: Photoinduced Molecular Transformations. Part 134. Photoinduced Stereospecific Addition of Methanol to 5β‐Cholest‐1‐en‐3‐one Oxime and Photoinduced Deconjugation of Its 1‐Methyl Derivative Involving Stereospecific Proton Transfer.

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