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Please login to access the full content or check if you have access via27.24.3.2.1.1 Variation 1: α,β-Unsaturated Esters (or Amides) by a Three-Component Reaction of Alcohols (or Amines), Aldehydes, and (Triphenylphosphoranylidene)ketene
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Schobert, R.; Gordon, G. J., Science of Synthesis, (2004) 27, 1050.
E-Configured α,β-unsaturated esters 161 (X = O) are obtained in good yields when three-component mixtures of the ylide 46, an alcohol and an aldehyde are refluxed for a few hours. The reaction proceeds by initial addition of the alcohol across the Cα=Cβ bond of the ylide 46 to give the corresponding ester ylide 160, which then alkenates the aldehyde present in the mixture. Direct alkenation of the aldehyde by the starting ylide is too slow to be a competitive process (Scheme 57).[570–572] Analogously, E-α,β-unsaturated S-thioesters 161 (X = S) or amides 161 (X = N) are accessible by reacting mixtures of the starting ylide, an aldehyde, and a thiol or an amine, respectively. This three-component reaction also works well with dialdehydes or aldehyde hydrates; for example, with glyoxal hydrate to give (E,E)-muconates.[570] It can be extended by further domino steps such as Diels–Alder cycloadditions; for example, four-component syntheses of cyclic γ,δ-unsaturated esters from mixtures of the ylide 146, an aldehyde, an alcohol and a 1,3-diene have been reported.[570] Most of this chemistry can be carried out under microwave conditions to shorten reaction times.[573]
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References
| [570] | Meeeeeee, M. M.; Meeeeeee, M., Meeee. Meee., (8888) 88, 888; Meeee. Meee. Mee. Me. Meee., (8888) 88, 888. |
| [571] | Meeeeeee, M.; Meeeeeeee, M.; Meeeee, M. M., M. Meee. Mee., Meeeee Meeee. 8, (8888), 8888. |
| [572] | Meeeee, M.; Mee, M.; Meeeeeee, M., Meee. Meeee. Meee., (8888) 88, 8888. |
| [573] | Meeeeee, M.; Meeeeee, M., Meee. Meee. Meee Meeeeeeeee Meeeeeeee, (8888) 8, 888. |
| [574] | Meee, M., Meeeeee Meeeeeee, Meeeee Meeeeeeeee Meeee: Mee Meee, (8888); e 888. |
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- 8.Meeeee-Meee, (8888) M 8, 888.
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