6165-52-2Relevant academic research and scientific papers
Cascade Reductive Friedel-Crafts Alkylation Catalyzed by Robust Iridium(III) Hydride Complexes Containing a Protic Triazolylidene Ligand
Albrecht, Martin,Alshakova, Iryna D.
, p. 8999 - 9007 (2021/07/31)
The synthesis of complex molecules like active pharmaceutical ingredients typically requires multiple single-step reactions, in series or in a modular fashion, with laborious purification and potentially unstable intermediates. Cascade processes offer attractive synthetic remediation as they reduce time, energy, and waste associated with multistep syntheses. For example, triarylmethanes are traditionally prepared via several synthetic steps, and only a handful of cascade routes are known with limitations due to high catalyst loadings. Here, we present an expedient catalytic cascade process to produce triarylmethanes. For this purpose, we have developed a bifunctional iridium system as the efficient catalyst to build heterotriaryl synthons via reductive Friedel-Crafts alkylation from ketones, arenes, and hydrogen. The catalytically active species were generated in situ from a robust triazolyl iridium(III) hydride complex and acid and is composed of a metal-bound hydride and a proximal ligand-bound proton for reversible dihydrogen release. These complexes catalyze the direct hydrogenation of ketones at slow rates followed by dehydration. Appropriate adjustment of the conditions successfully intercepts this dehydration and leads instead to efficient C-C coupling and Friedel-Crafts alkylation. The scope of this cascade process includes a variety of carbonyl substrates such as aldehydes, (alkyl)(aryl)ketones, and diaryl ketones as precursor electrophiles with arenes and heteroarenes for Friedel-Crafts coupling. The reported method has been validated in a swift one-step synthesis of the core structure of a potent antibacterial agent. Excellent yields and exquisite selectivities were achieved for this cascade process with unprecedentedly low iridium loadings (0.02 mol %). Moreover, the catalytic activity of the protic system is significantly higher than that of an N-methylated analogue, confirming the benefit of the Ir-H/N-H hydride-proton system for high catalytic performance.
Bisulfate Salt-Catalyzed Friedel-Crafts Benzylation of Arenes with Benzylic Alcohols
Tang, Ren-Jin,Milcent, Thierry,Crousse, Benoit
, p. 14001 - 14009 (2018/11/23)
We report here a method of direct Friedel-Crafts benzylation of arenes with benzylic alcohols using cheap and readily available bisulfate salt as the catalyst in hexafluoroisopropanol. The catalytic system is powerful with a quite diverse group of functionalized arenes and benzylic alcohols. These mild conditions provide a straightforward synthesis of a variety of unsymmetrical diarylmethanes in high yield with good to high regioselectivity. An SN1 mechanism involving activation of the hydroxy group through a hydrogen bond is proposed.
A surprising substituent effect provides a superior boronic acid catalyst for mild and metal-free direct Friedel-Crafts alkylations and prenylations of neutral arenes
Ricardo, Carolynne L.,Mo, Xiaobin,McCubbin, J. Adam,Hall, Dennis G.
supporting information, p. 4218 - 4223 (2015/03/14)
The development of more general and efficient catalytic processes for Friedel-Crafts alkylations is an important objective of interest toward the production of pharmaceuticals and commodity chemicals. Herein, 2,3,4,5-tetrafluorophenylboronic acid was identified as a potent air- and moisture-tolerant metal-free catalyst that significantly improves the scope of direct Friedel-Crafts alkylations of a variety of slightly activated and neutral arenes, including polyarenes, with allylic and benzylic alcohols. This method also provides a simple alternative for the direct installation of prenyl units commonly found in naturally occurring arenes. Alkylations with benzylic alcohols occur under exceptionally mild conditions.
Hydroarylation of styrenes with electron-rich arenes over acidic ion-exchange resins
Wen, Jingyun,Qi, Haofei,Kong, Xiangjin,Chen, Ligong,Yan, Xilong
, p. 1893 - 1903 (2014/07/07)
A series of acidic cation-exchange resins were used for the hydroarylation of resorcinol with styrene, in which resin D072 exhibited the excellent catalytic performance in this reaction with 99% conversion of styrene and 90% selectivity of 4-(1-phenylethyl)resorcinol. It was applied to the hydroarylation of various electron-rich arenes with styrenes, and the hydroarylated products were quantitatively obtained. This catalyst could be used for four consecutive runs with slight decrease in activity. The hydroarylation of resorcinol with styrene over resin D072 in a fixed bed was completed effectively with 94% selectivity and 99% conversion, and this green continuous process is potentially applicable to large-scale productions.
Iron-catalyzed arylation of aromatic ketones and aldehydes mediated by organosilanes
Savela, Risto,Majewski, Marcin,Leino, Reko
, p. 4137 - 4147 (2014/07/08)
A simple and efficient iron-catalyzed method for arylation of aromatic carbonyl compounds is reported. The use of 4-% FeCl3 or Fe(acac) 3 as the catalyst, in combination with a slight excess of chlorotrimethylsilane and triethylsilane, chlorination of benzylic ketones and aldehydes with subsequent Friedel-Crafts alkylation of arenes is achieved. Although the method is limited by the general constraints associated with Friedel-Crafts alkylation reactions, robust applications for the synthesis of pharmaceutical intermediates and so on can be envisioned. A robust one-pot, iron-catalyzed chlorination Friedel-Crafts alkylation reaction of benzylic carbonyl compounds, mediated by chlorotrimethylsilane and triethylsilane, has been developed to yield substituted diaryl and triaryl building blocks. Copyright
Synthesis of diarylmethanes via a Friedel-Crafts benzylation using arenes and benzyl alcohols in the presence of triphenylphosphine ditriflate
Khodaei, Mohammad Mehdi,Nazari, Ehsan
experimental part, p. 5131 - 5135 (2012/09/22)
Triphenylphosphine ditriflate (TPPD) was found to be an efficient promoter for the Friedel-Crafts benzylation of arenes with benzyl alcohols in CH 2Cl2 at room temperature. The good yields, the 1:1 molar ratio of arene and benzyl alcohol, the benzylation of chlorobenzene as a nonactivated aromatic compound at room temperature, and no by-product formation are the main advantages of this procedure.
A novel InCl3/SiO2-catalyzed hydroarylation of arenes with styrenes under solvent-free conditions
Sun, Gaojun,Sun, Huayin,Wang, Zhiyong,Zhou, Ming-Ming
experimental part, p. 1096 - 1100 (2009/04/04)
A novel InCl3/SiO2-catalyzed hydroarylation of various styrenes with arenes has been developed. The reaction can be carried out under solvent-free conditions to afford a series of 1,1-diarylalkanes in high yields and with good regioselectivities. The catalyst can be reused six times without obvious loss of catalytic activity. Georg Thieme Verlag Stuttgart.
An efficient and selective hydroarylation of styrenes with electron-rich arenes, catalyzed by bismuth(III) chloride and affording Markovnikov adducts
Sun, Hong-Bin,Li, Biao,Hua, Ruimao,Yin, Gwu
, p. 4231 - 4236 (2007/10/03)
In the presence of BiCl3, the hydroarylation of styrenes with electron-rich arenes afforded Markovnikov adducts selectively in good to high yields. Under arene-free conditions, the intermolecular hydroarylation of α-substituted styrenes and subsequent intramolecular hydroarylation produced the cyclic dimers of α-substituted styrenes in good yields. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
REACTION OF DISUBSTITUTED AROMATIC COMPOUNDS WITH STYRENE
Grushin, A. I.,Grigor'ev, V. V.,Prokof'ev, K. V.,Kozlova, N. M.
, p. 1939 - 1941 (2007/10/02)
Hydrocarbons of the 1,1-diphenylethane typr vere obtained by the reaction of styrene with various disubstituted derivatives of benzene in the presence of titanium tetrachloride.It was found that the yield of the desired compound depends on the strength of the electron-donating substituents and on steric factors in the aromatic ring.
