Lithium enolate
WebSome bases that have been used for enolate anion formation are: NaH (sodium hydride, pK a > 45), NaNH 2 (sodium amide, pK a = 34), and LiN [CH (CH 3) 2] 2 (lithium … WebFormation mechanism of acetaldehyde lithium enolate by reaction of n -butyllithium with tetrahydrofuran: infrared and Raman spectroscopy and density functional theory calculations. Journal of Raman Spectroscopy 2002, 33 (8) , 652-668.
Lithium enolate
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Web21 okt. 2000 · The cesium (1-Cs, CsPhPAT) and lithium (1-Li, LiPhPAT) enolates of 2,6-diphenyl-α-tetralone, 1, and the lithium enolate (2-Li, LiPhAT) of 2-phenyl-α-tetralone, 2, are present in dilute THF solution as monomers and dimers with K1,2 = 1810 (1-Cs, CsPhPAT), 2650 (1-Li, LiPhPAT), and 1930 (2-Li, LiPhAT) M-1. These values were … WebThe reaction of the free enolate CH2=CHO− with MeCl has an early transition state with low barrier, and the reaction of its lithium enolate gave a cyclic transition structure with high ...
WebAlso, in 1958 Nesmeyanov, Lutsenko, and Khomutov [11] reported on the properties of the simplest lithium enolate-lithium vinyloxide, CH 2 =OHOLi. This compound was prepared by the cleavage of the mercury derivative of acetaldehyde by the action of … WebA typical modern aldol addition reaction, shown above, might involve the nucleophilic addition of a ketone enolate to an aldehyde.Once formed, the aldol product can sometimes lose a molecule of water to form an α,β-unsaturated carbonyl compound.This is called aldol condensation.A variety of nucleophiles may be employed in the aldol reaction, including …
WebStructures of LDA/Lithium Enolate Mixed Aggregates. Analyses of [6Li,15N]LDA (0.1 M) with 1.0 equiv of ester 1-d120 at -90 °C in THF, HMPA/THF, and DMPU/THF reveal exclusively LDA dimers 3b-d.21 Warming the samples periodi-cally to -50 °C and cooling back down to -90 °C reveals mixed dimers 7b-d, each displaying a characteristic 6Li doublet Web19 jan. 2004 · We first decided to investigate the aldol reaction between non-fluorinated octyl acetate 3 and 2-fluorobenzaldehyde (5) in an attempt to develop a standard protocol ().The corresponding lithium enolate of octyl acetate was formed by slow addition of lithium diisopropylamide (LDA) to a solution of 3 in THF at -78 o C [].Addition of …
Web23 feb. 2024 · Meanwhile, a single crystal obtained from the reaction mixture of p-CF 3 benzoate and BnCH 2 C(Bpin) 2 Li was determined to be the α-boryl lithium enolate I-B (dimer in the crystal structure).
Web19 affords an equilibrium mixture of 1 and enolate 4. The high yields of alkylated product derive from a relatively slow enolization followed by an efficient trapping of enolate 4 with CH3I. We also show, however, that this seemingly simple transformation belies a complex ensemble of lithium enolate mixed aggregates. Moreover, an NMR ... cindy lee nail schoolWeb29 jun. 2011 · DFT computational study on the alkylation of the lithium enolate derived from acetaldehyde with MeCl was performed. The reaction of the free enolate CH 2 =CHO − with MeCl has an early transition state with low barrier, and the reaction of its lithium enolate gave a cyclic transition structure with high activation energy; neither of them is a … diabetic breakfast ideas low carbSilyl enol ethers are neutral, mild nucleophiles (milder than enamines) that react with good electrophiles such as aldehydes (with Lewis acid catalysis) and carbocations. Silyl enol ethers are stable enough to be isolated, but are usually used immediately after synthesis. Lithium enolates, one of the precursors to silyl enol ethers, can also be gener… cindy leeper facebook linkedinWeb21 aug. 2013 · The reactivity of the enolates follows the sequence monomer≫dimer>tetramer. In lithium aggregates, the initially formed aldol adducts must rearrange to form more stable structures in which the enolate and alkoxide oxygen atoms are within the respective Li n O n clusters. cindy lee montereyWebLithium enolate formation can be generalized as an acid–base reaction, in which the relatively acidic proton α to the carbonyl group (pK =20-28 in DMSO) reacts with … diabetic breakfast menuWebCyclohexanone lithium enolate Compare the geometries of the cyclohexanone enolate and the cyclohexanone lithium enolate. Do both molecules show delocalized structures, or is the bonding in one of them more localized For comparison, examine the geometries of 1-hydroxycyclohexene md cyclohexanone. Electrostatic potential map for cyclohexanone … diabetic breakfast ideas oatmealWebAn unprecedented stereoselective synthesis of trisubstituted vinylboronates is reported to proceed by direct borylation of lithium ketone enolates under transition-metal-free conditions. The stereospecific C−O borylation of lithium enolates was triggered by a carbonyl-induced 1,3-metalate rearrangement via a C-bound boron enolate. cindy lee norgate