18864-76-1Relevant articles and documents
Enantioselective Synthesis of Bicyclopentane-Containing Alcohols via Asymmetric Transfer Hydrogenation
Vyas, Vijyesh K.,Clarkson, Guy J.,Wills, Martin
supporting information, p. 3179 - 3183 (2021/05/04)
Compounds a containing bicyclo[1.1.1]pentane (BCP) adjacent to a chiral center can be prepared with high enantiomeric excess through asymmetric transfer hydrogenation (ATH) of adjacent ketones. In the reduction step, the BCP occupies the position distant from the η6-arene of the catalyst. The reduction was applied to the synthesis of a BCP analogue of the antihistamine drug neobenodine.
Nickel/Photoredox-Catalyzed Methylation of (Hetero)aryl Chlorides Using Trimethyl Orthoformate as a Methyl Radical Source
Kariofillis, Stavros K.,Shields, Benjamin J.,Tekle-Smith, Makeda A.,Zacuto, Michael J.,Doyle, Abigail G.
supporting information, p. 7683 - 7689 (2020/04/22)
Methylation of organohalides represents a valuable transformation, but typically requires harsh reaction conditions or reagents. We report a radical approach for the methylation of (hetero)aryl chlorides using nickel/photoredox catalysis wherein trimethyl orthoformate, a common laboratory solvent, serves as a methyl source. This method permits methylation of (hetero)aryl chlorides and acyl chlorides at an early and late stage with broad functional group compatibility. Mechanistic investigations indicate that trimethyl orthoformate serves as a source of methyl radical via β-scission from a tertiary radical generated upon chlorine-mediated hydrogen atom transfer.
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.
Erbium trifluoromethanesulfonate catalyzed Friedel-Crafts acylation using aromatic carboxylic acids as acylating agents under monomode-microwave irradiation
Tran, Phuong Hoang,Hansen, Poul Erik,Nguyen, Hai Truong,Le, Thach Ngoc
, p. 612 - 618 (2015/02/19)
Erbium trifluoromethanesulfonate is found to be a good catalyst for the Friedel-Crafts acylation of arenes containing electron-donating substituents using aromatic carboxylic acids as the acylating agents under microwave irradiation. An effective, rapid and waste-free method allows the preparation of a wide range of aryl ketones in good yields and in short reaction times with minimum amounts of waste.
Microwave-assisted facile and rapid friedel-crafts benzoylation of arenes catalyzed by bismuth trifluoromethanesulfonate
Tran, Phuong Hoang,Hansen, Poul Erik,Pham, Thuy Thanh,Huynh, Vy Thanh,Huynh, Vy Hieu,Thi Tran, Thao Du,Huynh, Thanh Van,Le, Thach Ngoc
, p. 2921 - 2929 (2014/10/15)
The catalytic activity of metal triflates was investigated in Friedel-Crafts benzoylation under microwave irradiation. Friedel-Crafts benzoylation with benzoyl chloride of a variety of arenes containing electron-rich and electron-poor rings using bismuth triflate under microwave irradiation is described. This method allows the preparation of aryl ketones under solventless conditions in good to excellent yields and short reaction time. Bismuth triflate was easily recovered and reused five times without significant loss of the catalytic activity.
DMC mediated one pot synthesis of biaryl ketones from aryl carboxylic and boronic acids
Pathak, Arunendra,Rajput, Chatrasal S.,Bora, Pushkar S.,Sharma, Somesh
, p. 2149 - 2150 (2013/05/08)
Synthesis of biaryl ketones has been realized from aryl carboxylic acids in the presence of DMC, facilitated by palladium catalyst under thermal condition. This methodology gives the introduction of carbonyl functionality in one pot from corresponding ary
Ag-catalyzed stereoselective cyclohexadienyl transfer: A novel entry into arylphenylmethanols
Umeda, Rui,Studer, Armido
supporting information; experimental part, p. 993 - 996 (2009/04/07)
The letter describes a novel concept for the synthesis of biologically important arylphenylmethanols. Stereoselective cyclohexadienyl transfer from 1,4-cyclohexadienyltributyltin to various aromatic aldehydes using AgOTf/BINAP as a catalyst precursor provides 1,4-cyclohexadienylphen-ylmethanols that are readily oxidized to the corresponding arylphenylmethanols. Fifteen examples are presented.
Decatungstate catalyst supported on silica and γ-alumina: Efficient photocatalytic oxidation of benzyl alcohols
Tzirakis, Manolis D.,Lykakis, Ioannis N.,Panagiotou, George D.,Bourikas, Kyriakos,Lycourghiotis, Alexis,Kordulis, Christos,Orfanopoulos, Michael
, p. 178 - 189 (2008/09/18)
Four supported catalysts with the same tungsten loading were prepared by depositing decatungstate species W10O4-32, through wet impregnation, on the surface of γ-alumina and silica at different pH values. The prepared samples were characterized using BET measurements as well as XRD, UV-vis DR, and XP spectroscopies. Higher dispersion of W(VI) oxo-species was obtained in the silica-supported catalysts compared with the corresponding alumina-supported ones. Within the same support, the dispersion was higher when the impregnation pH is lower than the point of zero charge (pzc) of the support. The decatungstate anions were present mainly on the silica surface without any modification, whereas these underwent a partial depolymerization on their deposition on the γ-alumina surface. The extent of depolymerization was less in the sample prepared at pH above pzc. These findings were explained in terms of the mode of deposition of the W(VI) species from the solution onto the support surface. The photocatalytic activity of the aforementioned catalysts, concerning the photooxidation of 1-phenylethanol, depends on the fraction of the W10O4-32 supported species rather than on the W(VI) dispersion. Thus, extremely high conversions have been obtained over the silica-based catalysts and also over the γ-alumina-based catalyst prepared at relatively high pH. These catalysts also are very effective in the photooxidation of a series of secondary and primary benzyl alcohols, in which benzyl ketones and benzoic acids were formed as the only or major products, respectively. The easy separation of the solid catalyst from the reaction mixture, the high activity, selectivity, and stability as well as the retained activity in subsequent catalytic cycles, make these supported catalysts suitable for a small-scale synthesis. Based on product analysis and kinetic data on the heterogeneous oxidation of benzyl alcohols, we suggest that a hydrogen abstraction transfer (HAT) mechanism predominates with respect to an electron transfer (ET) one in these reactions.
Friedel-crafts benzoylation of alkylbenzenes with brazoic anhydride catalyzed by solid superacids
Nakamura, Hideo,Arata, Kazushi
, p. 1893 - 1896 (2007/10/03)
The liquid-solid phase benzoylation of mono-alkylbenzenes with methyl, ethyl, propyl, and butyl groups and xylenes was carried out with benzoic anhydride at 100-110°C over solid superacids: SO4/ZrO 2, WO3/ZrO2, and SO4/ HfO 2. The reactivity ratio obtained by the competitive method of reaction over WO3/ZrO2 was 1 to 4.6 for toluene to p-xylene and 1.1:10:1 among o-, m-, and p-xylenes, respectively. Although the SO4/ZrO2 catalyst gave high yields of 92 and 97% for toluene and ethylbenzene in a 3:7 distribution of o- and p-isomers, respectively, low yields were observed with propyl and butylbenzenes over the catalyst: that is, 5 and 2% for propylbenzene and isopropylbenzene, 14% for isobutylbenzene, and trace yields for butylbenzene, s-butylbenzene, and t-butylbenzene, respectively. The usual Friedel-Crafts benzoylation using AlCl3 was examined in the present alkylbenzenes in order to confirm the low reactivity of both propyl and butylbenzenes. The results were similar to those with the SO4/ZrO2 catalyst; that is, the yields at 0°C for 1 h were 37, 21, 6, 1, 0, 3, and 2% for toluene, ethylbenzene, propylbenzene, isopropylbenzene, butylbenzene, s-butylbenzene, and t-butylbenzene, respectively, showing an unexpected result where there was no distinction between homogeneous and heterogeneous conditions.
Enantioselective oxidation of diaryl carbinols by Nocardia corallina B-276
Perez, Herminia I.,Luna, Hector,Manjarrez, Norberto,Solis, Aida,Nuez
, p. 4263 - 4268 (2007/10/03)
Whole cells of Nocardia corallina B-276 oxidized diaryl carbinols enantioselectively to give ketones in moderate yields, and some of the unreacted alcohols showed high ee's. This asymmetric oxidation is a simple and efficient method for preparing meta- and para-monosubstituted optically active diaryl carbinols from the racemates. The para-substituted chiral alcohols have an R configuration. (C) 2000 Elsevier Science Ltd.
