Silyl enol ether 5603128 213885529 2008-05-21T05:24:03Z 85.178.197.234 [[Image:Silyl enol ether.png|thumb|right|100px|The general structure of a silyl enol ether]] '''Silyl enol ethers''' in [[organic chemistry]] are a class of [[organic compound]]s sharing a common [[functional group]] composed of an [[enolate]] bonded through its [[oxygen]] terminus to an [[organosilicon]] group. Silyl enol ethers are important intermediates in [[organic synthesis]]. ==Organic synthesis== * Trimethylsilyl enol ethers can be prepared from ketones in presence of a strong base and [[trimethylsilyl chloride]]. * Silyl enol ether can form by capturing any [[enolate]] formed in a [[nucleophilic conjugate addition]]. <ref>[[Organic Syntheses]], Coll. Vol. 9, p.564 (1998); Vol. 73, p.123 (1996) [http://www.orgsynth.org/orgsyn/prep.asp?prep=cv9p0564 Article]</ref><ref>[[Organic Syntheses]], Coll. Vol. 8, p.277 (1993); Vol. 66, p. 43 (1988) [http://www.orgsynth.org/orgsyn/prep.asp?prep=cv8p0277 Article].</ref> * A rather exotic way to generate silyl enol ethers is via the [[Brook rearrangement]] of appropriate substrates. <ref> R. Tong, F. E. McDonald, [[Angewandte Chemie]], Int. Ed. 2008, 47, 1-4.</ref> ==Organic reactions== Silyl enol ethers react as [[nucleophile]]s in: * [[Mukaiyama aldol addition]] * [[Michael reaction]]s * [[Alkylation]]s * [[Haloketone]] formation with [[halogen]]s<ref>[[Organic Syntheses]], Coll. Vol. 8, p.286 (1993); Vol. 69, p.129 (1990) [http://www.orgsynth.org/orgsyn/prep.asp?prep=cv8p0286 Article]</ref> * [[Acyloin]] formation by [[organic oxidation]] with [[mCPBA]]<ref>[[Organic Syntheses]], Coll. Vol. 7, p.282 (1990); Vol. 64, p.118 (1986) [http://www.orgsynth.org/orgsyn/prep.asp?prep=cv7p0282 Article]. </ref> ===Saegusa oxidation=== In the '''Saegusa oxidation''' certain silyl enol ethers are oxidized to [[enone]]s with [[palladium(II) acetate]]. In the original publication <ref>''Synthesis of alpha, beta-unsaturated carbonyl compounds by palladium(II)-catalyzed dehydrosilylation of silyl enol ethers'' Yoshihiko Ito, Toshikazu Hirao, and Takeo Saegusa [[J. Org. Chem.]]; '''1978'''; 43(5) pp 1011 - 1013; {{DOI|10.1021/jo00399a052}}</ref> the amount of palladium is less than stochiometric and [[1,4-Benzoquinone|1,4-benzoquinone]] is used as [[sacrificial catalyst]]. The intermediate is an [[allylpalladium|oxo-allylpalladium complex]]. :[[Image:SaegusaOxidation.png|350px|Saegusa oxidation]] In one application a dienenone is synthesized in two steps from a cyclohexanone <ref>''Formation of Benzo-Fused Carbocycles by Formal Radical Cyclization onto an Aromatic Ring'' Derrick L. J. Clive and Rajesh Sunasee [[Org. Lett.]]; '''2007'''; 9(14) pp 2677 - 2680; (Letter) {{DOI|10.1021/ol070849l}}</ref> <ref>reagents in step 1 are [[trimethylsilyl triflate]] and [[2,6-lutidine]]</ref>: :[[Image:SaegusaApplication.png|400px|Saegusa application Clive 2007]] ==Ketene silyl acetals== '''Ketene silyl acetals''' are related compounds formally derived from [[ketene]]s and [[acetal]]s with general structure R-C=C(OSiR<sub>3</sub>)(OR'). ==References== <references/> [[Category:Functional groups]] [[es:Éter silílico de enol]]