2040-15-5Relevant articles and documents
An efficient and green method for regio- and chemo-selective Friedel-Crafts acylations using a deep eutectic solvent ([CholineCl][ZnCl2]3)
Tran, Phuong Hoang,Nguyen, Hai Truong,Hansen, Poul Erik,Le, Thach Ngoc
, p. 37031 - 37038 (2016/05/24)
[CholineCl][ZnCl2]3, a deep eutectic solvent between choline chloride and ZnCl2, has been used as a dual function catalyst and green solvent for the Friedel-Crafts acylation of aromatic compounds instead of using the moisture-sensitive Lewis acids and volatile organic solvents. The reactions are performed with high yields under microwave irradiation with short reaction times for the synthesis of ketones. Interestingly, indole derivatives are regioselectively acylated in the 3-position under mild conditions with high yields without NH protection. Three new ketone products are synthesized. [CholineCl][ZnCl2]3 is easily synthesized from choline chloride and zinc chloride at a low cost, with easy purification and environmentally benign compounds. [CholineCl][ZnCl2]3 can be reused up to five times without loss of catalytic activity, making it ideal in industrial processes.
Synthetic utility of iodic acid in the oxidation of benzylic alcohols to aromatic aldehydes and ketones
Imai, Sho,Togo, Hideo
, p. 6948 - 6954 (2016/10/13)
Various primary and secondary benzylic alcohols were efficiently oxidized to aromatic aldehydes and aromatic ketones with iodic acid in DMF at 60?°C for 2?h and with iodic acid in the presence of TEMPO (5?mol?%) in DMF at room temperature, respectively. The former method was effective for the oxidation of sterically hindered alcohols at 60?°C and the latter method was effective for the oxidation of less sterically hindered alcohols at room temperature.
Pentamethylcyclopentadienyl ruthenium: an efficient catalyst for the redox isomerization of functionalized allylic alcohols into carbonyl compounds
Bouziane, Asmae,Carboni, Bertrand,Bruneau, Christian,Carreaux, Fran?ois,Renaud, Jean-Luc
experimental part, p. 11745 - 11750 (2009/04/11)
The catalytic activity of the ruthenium(II) complex [RuCp*(CH3CN)3][PF6] 1 in the transposition of allylic alcohols into carbonyl compounds, in acetonitrile, is reported. This catalyst has proven to be able to catalyze the transformation of poorly reactive and/or functionalized substrates under smooth conditions.
Hafnium(IV)Trifluoromethanesulfonate, An Efficient Catalyst for the Friedel-Crafts Acylation and Alkylation Reactions
Hachiya, Iwao,Moriwaki, Mitsuhiro,Kobayashi, Shu
, p. 2053 - 2060 (2007/10/02)
Hafnium(IV) trifluoromethanesulfonate (hafnium(IV) triflate, Hf(OTf)4) was synthesized from hafnium tetrachloride and trifluoromethanesulfonic acid.The triflate thus prepared was found to be effective in the catalytic Friedel-Crafts acylation reactions of various substituted benzenes with acid anhydrides in lithium perchlorate-nitromethane (LiClO4-MeNO2).Lithium perchlorate-nitromethane is an excellent solvent system, and the catalytic activity of the Lewis acid was much improved in this medium.The product was obtained in up to 250000percent molar amounts baaed on the catalyst.Hafnium(IV) triflate was also found to be quite effective in the catalytic Friedel-Crafts alkylation reactions of aromatic compounds with alkyl chlorides.The reactions proceeded smoothly in the presence of 5percent molar amount of Hf(OTf)4 and 50percent molar amount of LiClO4 by using a slow addition procedure.
A Novel Friedel-Crafts Reaction of Hindered Ketones
Roberts, Royston M.,El-Khawaga, Ahmed M.,Roengsumran, Sophon
, p. 3180 - 3183 (2007/10/02)
Mesitylene has been shown to react with acetyl chloride in the presence of aluminium chloride to form 1,1-dimesitylethene.Acetomesitylene has been demonstrated to be an intermediate in the reaction, which proceeds in the second step by nucleophilic attack by the arene on the carbonyl group of acetomesitylene, which is activated by the formation of a polarized complex with aluminum chloride.Mesitylene reacts similarly with propionyl chloride, forming 1,1-dimesitylpropene; propiomesitylene is an intermediate.Steric and electronic factors responsible for this unique Friedel-Crafts reaction are discussed.
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.
Acyclic Stereoselection. 7. Stereoselective Synthesis of 2-Alkyl-3-hydroxy Carbonyl Compounds by Aldol Condensation
Heathcock, Clayton H.,Buse, Charles T.,Kleschick, William A.,Pirrung, Michael C.,Sohn, John E.,Lampe, John
, p. 1066 - 1081 (2007/10/02)
The stereochemistry of the aldol condensation of preformed lithium enolates of a variety of ethyl ketones and propionic acid derivatives with aldehydes has been investigated.It is found that certain compounds give completely or nearly completely one diastereomeric enolate and that the stereostructure of the resulting aldol is correlated with the stereostructure of the enolate from which is formed.The observed stereochemistry may be understood in terms of an ordered transition state in which both oxygens are oriented in more or less the same direction.It is shown that the observed stereochemistry is kinetically controlled.In many cases, the initial aldol adduct equilibrates to furnish predominantly a threo isomer.The rate of equilibration varies widely, ranging from very fast at -60 deg C with the propiophenone-benzaldehyde adduct to slow at 25 deg C for the ethyl tert-butyl ketone-benzaldehyde adduct.The equilibration behavior of lithium ketolates is compared with that of zinc ketolates, and some differences are noted.A method for achieving erythro-threo equilibration via a chloral hemiacetal is presented.A new reagent is introduced (trimethylsilyloxy ketone 36) which may be used to stereoselectively homologate an aldehyde to an erythro α-methyl-β-hydroxy acid.As an application of the use of stereoselective aldol condensations in synthesis, (+/-)-ephedrine (48) has been synthesized from benzaldehyde in 71 percent overall yield.
