Light-Induced Chemistry of Oximes and Derivatives
Hydroxylamines, Oximes and Hydroxamic Acids (2010)
Published Online: 15 SEP 2010
Copyright © 2009 John Wiley & Sons, Ltd. All rights reserved.
Patai's Chemistry of Functional Groups
How to Cite
D. Roth, H. 2010. Light-Induced Chemistry of Oximes and Derivatives. Patai's Chemistry of Functional Groups. .
- Published Online: 15 SEP 2010
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.
- Light-induced chemistry of oximes and derivatives;
- HEINZ D. ROTH;
- E, Z isomerization;
- photo-Beckmann rearrangement;
- oxazirane formation;
- O–H cleavage;
- N–O cleavage;
- aza-di-π-methane rearrangement;
- isoxazoline formation;
- iminoxyl radical;
- iminyl radial;
- steroidal oximes;