2040-22-4Relevant academic research and scientific papers
Rhenium(I)-Catalyzed C-Methylation of Ketones, Indoles, and Arylacetonitriles Using Methanol
Shee, Sujan,Kundu, Sabuj
, p. 6943 - 6951 (2021/05/29)
A ReCl(CO)5/MeC(CH2PPh2)3 (L2) system was developed for the C-methylation reactions utilizing methanol and base, following the borrowing hydrogen strategy. Diverse ketones, indoles, and arylacetonitriles underwent mono-and dimethylation selectively up to 99% yield. Remarkably, tandem multiple methylations were also achieved by employing this catalytic system.
Preparation of Benzocyclobutenones via the Photochemical Cyclization of 1-(ortho-Alkylary)-2,2,4-trimethylpentane-1,3-diones
Yoshioka, Michikazu,Momose, Shinobu,Nishizawa, Kaori,Hasegawa, Tadashi
, p. 499 - 503 (2007/10/02)
Irradiation of 1-(ortho-methylaryl)- and 1-(ortho-ethylaryl)-2,2,4-trimethylpentane-1,3-diones 4a-g in hexane gave benzocyclobutenols 10a-g.However, irradiation of 1-(ortho-isopropylaryl)-2,2,4-trimethylpentane-1,3-diones 4i and 4j resulted in no reaction.Irradiation of 1-mesityl-2,2,4-trimethylpentane-1,3-dione 4h gave a complex mixture of products.Pyrolysis of benzocyclobutenols 10a, b, d-f gave benzocyclobutenones 11a, b, d-f and 2,4-dimethylpentan-3-one 2, whereas that of the benzocyclobutenols 10c, g gave the starting 1,3-diketones 4c, g predominantly along with small amounts of benzocyclobutenones 11c, g and the dimethylpentanone 2.
Carboxylic Trifluoromethanesulfonic Anhydrides as Highly Effective Acylation Agents. - Perfluoroalkanesulfonic Acid Catalyzed Acylation of Arenes
Effenberger, Franz,Sohn, Erich,Epple, Gerhard
, p. 1195 - 1208 (2007/10/02)
Arene- and alkanecarboxylic trifluoromethanesulfonic anhydrides 2 and 5 are highly effective acylation agents, which react without Friedel-Crafts catalysts even with deactivated aromatics to yield aryl ketones 3 and 6, respectively.Acylation of arenes with carbonyl chlorides 4 and catalytic amounts of perfluoroalkanesulfonic acid gives ketones 3 and 6, resp., in good yields.Under similar conditions other strong Broensted acids show a considerably smaller degree of catalytic effect.
Studies on the Mechanism of the Enolization Reaction of Grignard Reagents and Ketones. Part 2. Pseudo-first-order Rate and Deuterium Isotope Effect Studies
Pinkus, George A.,Sabesan, Arunachalam
, p. 473 - 477 (2007/10/02)
Kinetics of enolization reactions of some alkyl mesityl ketones with alkylmagnesium bromides were studied under pseudo-first-order conditions by measuring formation of gaseous alkane.Using a large fixed excess of isopropyl mesityl ketone, the reaction was first order in ethylmagnesium bromide; with a fixed excess of ethylmagnesium bromide, the reaction was first order in ketone.At high excess variable concentrations of ketone, however, k2 values decreased with increasing ketone concentration in a good linear relation between the two variables.When both Grignard and ketone concentrations (at 1:1 mole ratios) were varied, a nonlinear relationship resulted between concentrations and k2 values.Rates did not vary significantly between highly pure and reagent grade magnesium.Reactions in tetrahydrofuran at b.p. 67 deg C took place at significantly slower rates than reactions in ether at b.p. 36 deg C at comparable concentrations whereas reactions in di-n-butyl ether at b.p. 141 deg C occurred at a much faster rate at higher concentrations.Reactions of α-deuterio-substituted methyl, ethyl, and isopropyl mesityl ketones with ethylmagnesium bromide showed isotope effects confirming breaking of the C-H bond as the rate-determining step in accord with the proposed mechanism.Values of kH/kD=2.6-3.1 indicate a moderate degree of C-H bond stretching in the transition state.A two-step mechanism is proposed.
