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Please login to access the full content or check if you have access via27.24.3.2.2 Method 2: Syntheses of E-α,β-Unsaturated Ketones by Tandem Grignard/Wittig Alkenation Reactions of (Triphenylphosphoranylidene)ketene
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Schobert, R.; Gordon, G. J., Science of Synthesis, (2004) 27, 1056.
(Triphenylphosphoranylidene)ketene 46 not only opens access to ester ylides (via addition of the respective alcohols to its Cα=Cβ bond), but also to acyl ylides by addition of carbon nucleophiles of the Grignard type. The metalated intermediates (possibly of the type 177) obtained upon heating mixtures of the cumulated ylide and pre-prepared Grignard solutions[25] are used immediately to alkenate carbonyl compounds to give E-2-enones 179, or can be first hydrolyzed to the corresponding acyl ylides 178, which are then subjected to Wittig alkenation in a separate step (Scheme 62). This is one of the few general approaches to highly functionalized and long-chain acyl ylides.[565] It is applied repeatedly as the key step in the syntheses of natural products such as the Queen's substance,[565] and pheromones of the peach fruit moth,[578] the Douglas fir tussock moth,[578] and the olive fly (Dacus oleae),[579] among others. Attempts to silylate or alkylate the metalated intermediates 177 have been, so far, unsuccessful.
Meeeee 88 Meee Meeeee eee M-8-Meeeee ee Meeeee Meeeeeee Meeeeeee–Meeeee Meeeeeeeee ee (Meeeeeeeeeeeeeeeeeeeeeeeee)eeeeee[88,888]
Meeeeeeeeeee Meeeeeeee
(Meeeeeeeeeeeeeeeee)eeeeeeeeeeeeeeeeeeee (888, M8 = Me):[888]
Me eeeeeeee (8.88 e, 888 eeee) eeee eeeeee ee e 8 M, 8-eeeeee eeeee eeeeeeee eeee e eeeee eeeeeeeee, eeeeeeeeee eeeeeee eee eeeeeeee eeeeee, eee eeeeeeeee ee ee eeeee eee eeeeeeeeee. MMM (888 eM) eee eeeee eee eee eeeeeeee eee eeeeeeeee ee eeeeee e eeeee eeeeee ee MeMe. Mee eeeeeee eeeeeee eeeeeee eee eeee eeeeeee eeeeeeee eeee e eeee ee MeMe (88.8 e, 888 eeee) ee MMM (88 eM) eee eeeeee ee eeeeee eeeee eee eee eeeee eee eeeeeeeee. M eeee ee (eeeeeeeeeeeeeeeeeeeeeeeeee)eeeeee (88.8 e, 88 eeee) ee MMM (888 eM) eee eeeee eeeeeeee eeee e eeeeee ee 88 e ee eee eeeeeee eeeeeee eeee ee MeMeMe eeee eeeeeeee, eee eeeeeeee eee eeeeeee eeee eeeeeeeee eee eeeeeee 8 e. Meeee eeeeeee ee ee, eee eeeeeee eee eeeeee ee eeee eeee ee ee eee. eeee ee MM8Me. Mee eeeeeee eeeee eee eeeeeeeee, eee eeeeeee eeeee eee eeeeeeeee eeeee eeee eeeeeee eee eee eeeeeeee eeeeeee eeeeee eeee eeeee (MeMM8), eeeeeeee, eee eeee eeeeeeeeee ee eeeeeee. Mee eeeeeee eee eeeee ee ee MM8Me8, eeeeee eeee eeeee eee eee eeee eeee eeeeeeee eee eeeee eeeee eee eeeeeeeeeeee eeeee eeeeeee eeeeeeee ee eeeee eeeeee eeeeeeee. Meeee eeee eeeeeeeeeeeeee (MeMMe/Me8M 8:8); eeeee: 88.8 e (88%); ee 888°M; 88M MMM (MMMe8, δ): 88.8.
References
[25] | Meeeeeee, M. M.; Meeeeee, M.; Meeeeeee, M., Meeee. Meee., (8888) 88, 888; Meeee. Meee. Mee. Me. Meee., (8888) 88, 888. |
[565] | Meeeeeee, M. M.; Meeeeee, M.; Meeeeeee, M., Meeeeeeee, (8888), 88. |
[578] | Meeeeeee, M. M.; Meeeeee, M., Meeeeeeeeee Meee., (8888) 88, 8888. |
[579] | Meeeeeee, M. M.; Meeeeee, M., Meeeeeeeeee Meee., (8888) 88, 8888. |