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Salaün, J., Science of Synthesis, (2005) 26, 641.
β,γ-Unsaturated ketones undergo a formal [1,2]-acyl shift from the lowest excited triplet state to give cyclopropyl ketones in high yields; this is sometimes termed an oxa-di-π-methane rearrangement.[175,176] Thus, acetone-sensitized irradiation of S-β,γ-unsaturated ketone 206 gives the R-cyclopropyl ketone 207 with 90% conversion (Scheme 72).[177] The optical purity of R-cyclopropyl ketone 207 is greater than 90% demonstrating its photostability. Due to the rearrangement occurring with inversion of configuration at the α-carbon, the excited state follows the allowed π2a + σ2a pathway.[177]
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References
[175] | Meeeee, M. M.; Meeeeeee, M. M., M. Me. Meee. Mee., (8888) 888, 8888. |
[176] | Meeee, M. M.; Meeeeee, M. M.; Meeeeeeee, M. M., Meee. Mee., (8888) 88, 888. |
[177] | Meeeee, M. M.; Meeeee, M. M.; Meeeeee, M. M., M. Me. Meee. Mee., (8888) 88, 8888. |
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