ORGN 125 |
| Photoinduced electron-transfer represents an attractive way of releasing carbonyl compounds from protected enols. This strategy is very useful for a variety of different applications, as different photoremovable protecting groups (PRPGs) can be used and the wavelength of light required to trigger the release can be controlled. Protected enols (alkyl enol ethers) were synthesized in 62–97% yields. Incorporating a 2-nitrobenzyl group as the chromophore (an excited state electron acceptor); the enol ethers were photolyzed in dry acetonitrile under air using 350 nm light. Analysis of the photoproducts by GC–MS revealed a C=C bond scission, that resulted in the formation of a ketone (about 60%), while the aldehyde (from tautomerization of the corresponding released enol) was obtained as a minor product. Based on product studies, it is speculated that a photoinduced intramolecular electron-transfer from the electron rich C=C bond to the electron deficient nitrobenzyl group, followed by 1,2-dioxetane formation, is responsible for the formation of the ketone or aldehyde. The intermolecular version of this reaction makes it possible for different electron acceptors to be explored, and offers flexibility to the synthesis of the alkyl enol ethers.
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Asymmetric Reactions and Syntheses, Physical Organic Chemistry, Combinatorial Chemistry, Total Synthesis
8:00 PM-10:00 PM, Sunday, 26 March 2006 Georgia World Congress Center -- Ex. Hall B4, Poster
Sci-Mix
Division of Organic Chemistry |
