766-66-5Relevant academic research and scientific papers
Diastereoselective Additions of Allylmagnesium Reagents to α-Substituted Ketones When Stereochemical Models Cannot Be Used
Bartolo, Nicole D.,Demkiw, Krystyna M.,Valentín, Elizabeth M.,Hu, Chunhua T.,Arabi, Alya A.,Woerpel
, p. 7203 - 7217 (2021/05/29)
The stereoselectivities of reactions of allylmagnesium reagents with chiral ketones cannot be easily explained by stereochemical models. Competition experiments indicate that the complexation step is not reversible, so nucleophiles cannot access the widest range of possible encounter complexes and therefore cannot be analyzed easily using available models. Nevertheless, additions of allylmagnesium reagents to a ketone can still be stereoselective provided that the carbonyl group adopts a conformation that leads to one face being completely blocked from the approach of the allylmagnesium reagent.
Infrared and theoretical calculations in 2-halocycloheptanones conformational analysis
Rozada, Thiago C.,Gauze, Gisele F.,Favaro, Denize C.,Rittner, Roberto,Basso, Ernani A.
experimental part, p. 277 - 287 (2012/07/14)
2-Halocycloheptanones (Halo = F, Cl, Br and I) were synthesized and their conformational analysis was performed through infrared spectroscopy data. The corresponding conformers geometries and energies were obtained by theoretical calculations at B3LYP/aug-cc-pVDZ level of theory in the isolated state and in solution. It was observed, by both approaches, that the conformational preferences were very sensitive to the solvent polarity, since its increase led to an increase in the population of the more polar conformer. An analysis of these conformational equilibria showed they suffer also the influence of stereoelectronic effects, like hyperconjugation and steric effects. These results were interpreted using natural bond orbital (NBO) analysis, which indicated that the electronic delocalization to the orbital π* CO is directly involved in the stability increase of conformers I and II. The relative effect of the period of the halogen can also be noted, with changes in the conformational preferences and in the energies involved in the interactions of NBO.
Rate coefficients and products for gas-phase reactions of chlorine atoms with cyclic unsaturated hydrocarbons at 298 K
Sharma,Pushpa,Dhanya,Naik,Bajai
body text, p. 98 - 105 (2011/06/21)
Rate coefficients for the reaction of Cl atoms with cycloalkenes have been determined using the relative rate method, at 298 K and atmospheric pressure of N2. Reference molecule was n -hexane, and the concentrations of the organics were followed by gas chromatographic analysis. Cl atoms were prepared by photolysis of trichloroacetyl chloride at 254 nm. The relative rates of reactions of Cl atoms with cycloalkenes, with, respect to M-hexane, are measured as 1.12 ±0.38, 1.31 ±0.14, and 1.69±0.18forcyclopentene, cyclohexene, and cycloheptene, respectively. Considering the absolute value of the rate coefficient of the reaction of Cl atom with n-hexane as 3.03 ± 0.06 × 10-10 cm3 molecule-1 s -1, the rate coefficient values for cyclopentene, cyclohexene, and cycloheptene are calculated, to be (3.39 ± 1.08) × 10 -10, (3.97 ±0.43) × 10-10, and (5.12 ± 0.55) × 10-10 cm3 molecule-1 S -1', respectively. The experiments for each, molecule were repeated six to eight times, and the slopes and the rate coefficients given above are the average values of these measurements, and the quoted error includes 2σ as well as all other uncertainties in the measurement and calculations. The rate coefficient increases linearly with the number of carbon atoms, with an increment per additional CH2 group being (8.7 ± 1.6) × 11-12 cm3 molecule-1 s-1. Chloroketones and chloroalcohols, along with unsaturated, ketones and alcohols, were found to be the major products of Cl-atom-initiated oxidation of cycloalkenes in the presence of air. The atmospheric implications of these results are discussed, along with a comparison with the reported structure activity relationships.
A safe, convenient and efficient one-pot synthesis of α-chloroketone acetals directly from ketones using iodobenzene dichloride
Yu, Jun,Zhang, Chi
body text, p. 2324 - 2328 (2010/01/13)
Various ketones, including aliphatic and aromatic ketones, can be directly converted into their corresponding α-chloroketone acetals in high to excellent yields using iodobenzene dichloride in ethylene glycol in the presence of 4 A molecular sieves at room temperature. Georg Thieme Verlag Stuttgart.
Rapid and catalyst-free α-halogenation of ketones using N-halosuccinamides in DMSO
Sreedhar,Reddy, P. Surendra,Madhavi
, p. 4149 - 4156 (2008/03/13)
α-Halogenation of various carbonyl compounds such as β-keto-esters, cyclic ketones, and lactams with N-halosuccinamides (NBS, NCS, NIS) in the presence of DMSO proceeded very smoothly to give the corresponding α-monohalogenated products in good to excellent yields with high selectivity under catalyst-free conditions. Copyright Taylor & Francis Group, LLC.
Halogenation of carbonyl compounds by an ionic liquid, [AcMIm]X, and Ceric Ammonium Nitrate (CAN)
Ranu, Brindaban C.,Adak, Laksmikanta,Banerjee, Subhash
, p. 358 - 362 (2008/02/13)
An ionic liquid, acetylmethylimidazolium halide ([AcMIm]X), in combination with ceric ammonium nitrate promotes halogenations of a wide variety of ketones and 1,3-keto esters at the ?-position. The ionic liquid acts here as reagent as well as reaction medium, and thus the reaction does not require any organic solvent or conventional halogenating agent. The reaction is completely arrested when the radical quencher TEMPO is used. A plausible radical mechanism is also suggested. CSIRO 2007.
Microwave-assisted synthesis of α-hydroxy ketone and α-diketone and pyrazine derivatives from α-halo and α,α′-dibromo ketone
Utsukihara, Takamitsu,Nakamura, Hiroaki,Watanabe, Masashige,Akira Horiuchi
, p. 9359 - 9364 (2008/01/27)
A novel reaction of α-halo ketone (α-bromo and α-chloro ketone) with irradiation under microwave gave the corresponding α-hydroxyketone and pyrazine derivative in good yields. In the case of α,α′-dibromo ketone, α-diketone was obtained. This reaction affords a new, clean and convenient synthetic method for α-hydroxyketone, α-diketone, α-chloro ketone and pyrazine derivative.
Amberlyst-15-promoted efficient 2-halogenation of 1,3-keto-esters and cyclic ketones using N-halosuccinimides
Meshram,Reddy,Sadashiv,Yadav
, p. 623 - 626 (2007/10/03)
A simple and rapid process has been developed for the α- monohalogenation of 1,3-keto-esters with N-halosuccinimides catalyzed by Amberlyst-15 at room temperature to produce the corresponding 2-halo 1,3-keto-esters in high yields. This protocol also extended to α-halogenation of cyclic ketones.
Addition of NOCl to cyclic vinylsilanes: An unexpected reversal of regiochemistry
Mallya, M. Narendra,Nagendrappa, Gopalpur,Shashidhara Prasad,Sridhar,Lokanath,Begum
, p. 2565 - 2568 (2007/10/03)
NOCl adds to cyclic vinylsilanes in a syn manner with NO+ bonding to the β-carbon and Cl- to the α-carbon, which is a reversal of the regiochemistry expected from the β-silicon effect. The adducts dimerize to a single diastereomer containing enantiomeric pairs and/or give secondary products on further reaction.
α-chlorination of ketones with sodium chlorite, Mn(acac)3, and alumina in dichloromethane
Yakabe, Shigetaka,Hirano, Masao,Morimoto, Takashi
, p. 131 - 138 (2007/10/03)
Chlorination of a variety of aliphatic, alicyclic, and aromatic ketones with a reagent combination of NaC1O2 and Mn(acac)3 catalyst can be readily performed in dichloromethane to afford α-chloroketones in good yield under mild and neutral conditions with the aid of chromatographic neutral alumina.
