13633-85-7Relevant academic research and scientific papers
Acid- And base-switched palladium-catalyzed γ-C(sp3)-H alkylation and alkenylation of neopentylamine
Zhang, Jinquan,Zhang, Shuaizhong,Zou, Hongbin
supporting information, p. 3466 - 3471 (2021/05/31)
The functionalization of remote unactivated C(sp3)-H and the reaction selectivity are among the core pursuits for transition-metal catalytic system development. Herein, we report Pd-catalyzed γ-C(sp3)-H-selective alkylation and alkenylation with removable 7-azaindole as a directing group. Acid and base were found to be the decisive regulators for the selective alkylation and alkenylation, respectively, on the same single substrate under otherwise the same reaction conditions. Various acrylates were compatible for the formation of C(sp3)-C(sp3) and C(sp3)-C(sp2) bonds. The alkenylation protocol could be further extended to acrylates with natural product units and α,β-unsaturated ketones. The preliminary synthetic manipulation of the alkylation and alkenylation products demonstrates the potential of this strategy for structurally diverse aliphatic chain extension and functionalization. Mechanistic experimental studies showed that the acidic and basic catalytic transformations shared the same six-membered dimer palladacycle.
How much does the hybridization of a carbon atom affect the transmission of the substituent effect on the chemical shift?
Jeong, Eun Jeong,Lee, In-Sook Han
, p. 295 - 299 (2015/03/03)
1H and 13C NMR spectra of aryl esters of propionic acid, acrylic acid, and propiolic acid were systematically examined to find out the substituent effect on the chemical shift. The values of the chemical shift of the carbonyl carbon showed an inverse correlation with the Hammett ?3 values, and the magnitude of the slope was the largest with the propiolates. The ?± carbons of acrylates and propiolates also showed an inverse correlation with much smaller values of the slopes than those of the carbonyl carbons; but those of the propionates showed absolutely no correlation. However, the ?2 carbons of acrylates and propiolates showed normal correlation with larger values of the slopes. The signs and the magnitudes of the slopes may be understood by the transmission of the substituent electronic effect through bonds as well as through space. The propiolyloxy group also showed a significantly large effect on the 13C chemical shift values of the benzene ring.
The 'Baylis - Hillman reaction' mechanism and applications revisited
Fort, Yves,Berthe, Marie Christine,Caubere, Paul
, p. 6371 - 6384 (2007/10/02)
It is shown that reaction of aryl, benzyl, alkyl and functionalised alkyl acrylic esters with benzaldehyde, in the presence of 1,4-diazabicyclo[2.2.2] octane, strongly depends upon the electronic and steric effects of the ester part. This influence is also observed in condensation of furfuraldehyde. Moreover, for the first time, it is shown that the overall condensation is equilibrated.
Dehydrobromination of Some Substituted Phenyl 3-Bromopropionates and Phenyl 3-Bromothiolopropionates. Transmission of Activation Effects through Acyl Bonds
Gilbert, Arthur B.,Peters, Frances B.,Johnson, H. W.
, p. 2724 - 2728 (2007/10/02)
Thirteen aryl 3-bromopropionates and nine aryl 3-bromothiolopropionates were prepared and subjected to dehydrohalogenation with sodium 3,4-dinitrophenoxide in dry tetrahydrofuran at 34.25 deg C.The second-order rate constants for the sulfur esters were approximately 10 times those for the corresponding oxygen esters.Good Hammett plots with ρ's of +0.81+/-0.04 and 0.98+/-0.04 for the oxygen and sulfur series, respectively, were obtained by using ?n.Activation parameters were measured for two oxygen and two sulfur esters; in both bases, low (12-13 kcal/mol) activatio n enthalpies and moderately large negative (19-21 eu) activation entropies were found.At 34.25 deg C, 3'-nitrophenyl 3-bromopropionate dehydrohalogenated 14 times more rapidly than 3'-nitrophenyl 3-chloropropionate; phenyl 3-bromothiolopropionate dehydrohalogenated 11 times more rapidly than the phenyl 3-chlorothiolopropionate.The rate constant ratio for 4'-bromophenyl 3-bromopropionate vs. 4'-bromophenyl 3-bromopropionate-2-d was 1.84; the monodeuterated compound yielded olefinic product with 65percent D.H was abstracted preferentially from 4'-chlorophenyl 3-bromothiolopropionate partially deuterated in the 2-position, but no kinetic results were obtained.No evidence of reversibility was found with 2,4-dinitrophenol-d, and the addition of 2,4-dinitrophenol to kinetic mixtures had essentially no effect on the rate conatants.The results are interpreted to indicate an E2 process near the EL/E1cB borderline with the thiolo ester deviating somewhat more toward an E1cB-I process.
