21895-16-9

Upstream product

• 13152-94-8 3,4'-dimethylbenzophenone 
• 104-82-5 4-Methylbenzyl chloride 
• 108-88-3 toluene 
• 620-19-9 1-chloromethyl-3-methyl-benzene 
• 106-42-3 para-xylene 
• 108-44-1 1-amino-3-methylbenzene 
• 104-87-0 4-methyl-benzaldehyde 
• 183156-71-0 N-(4-methylbenzyl)-N-nitrosoacetamide 
• 71-43-2 benzene 
• 5663-40-1 2-(4-methylphenyl)-1,3-dioxane 
• 31614-66-1 tributyl(p-tolyl)stannane 
• 824-79-3 sodium 4-methylbenzenesulfinate 
• 589-18-4 4-Methylbenzyl alcohol 
• 2216-45-7 p-methylbenzyl alcohol acetate 

Relevant academic research and scientific papers

N-heterocyclic carbene–palladium complexes for Suzuki–Miyaura coupling reaction with benzyl chloride and aromatic boronic acid leading to diarylmethanes

A family of N-heterocyclic carbene–palladium(II)–N,N-dimethylbenzylamine complexes ((NHC)LPdCl2; L?=?N,N-dimethylbenzylamine) were synthesized as well as characterized using single-crystal X-ray diffraction and spectroscopic data. These complexes exhibited higher catalytic activities for the Suzuki reaction of benzyl chlorides to afford diarylmethanes under milder conditions than other efficient (NHC)LPdCl2 complexes. Using the optimum conditions, the expected coupling products were obtained in moderate to high yields. All reactions were carried out in air and all starting materials were used as supplied without purification.

Benzylic Phosphates in Friedel-Crafts Reactions with Activated and Unactivated Arenes: Access to Polyarylated Alkanes

Easily reachable electron-poor/rich primary and secondary benzylic phosphates are suitably used as substrates for Friedel-Crafts benzylation reactions with only 1.2 equiv activated/deactivated arenes (no additional solvent) to access structurally and electronically diverse polyarylated alkanes with excellent yields and selectivities at room temperature. Specifically, diversely substituted di/triarylmethanes are generated within 2-30 min using this approach. A wide number of electron-poor polyarylated alkanes are easily accomplished through this route by just tuning the phosphates.

Benzylation of arenes with benzyl halides synergistically promoted by in situ generated superacid boron trifluoride monohydrate and tetrahaloboric acid

To examine the assembly methodology of diarylmethanes, a benzylation of (hetero)arenes with benzyl halides has been developed and various diarylmethanes were furnished with yields of up to 98% and regioselectivities of up to >99%. The complexation of the by-product halogen hydride with BF3·OEt2 generated the Bronsted acid BF3·HX (HBF3X, X=Cl or Br) in situ to synergistically promote the benzylation.

Synthesis of diarylmethanes through palladium-catalyzed coupling of benzylic phosphates with arylsilanes

An efficient approach to the benzylation of arenes has been developed. The reactions described provide straightforward access to diarylmethanes through Pd-catalyzed coupling of benzylic phosphates with arylsilanes in good to excellent yields. The reaction tolerates a wide range of functionalities such as halide, alkoxyl, and nitro groups.

Superacid BF3-H2O promoted benzylation of arenes with benzyl alcohols and acetates initiated by trace water

A convenient procedure employing simple starting materials benzyl alcohols and acetates as the benzyl donors to assemble a series of diarylalkanes through benzylation of arenes using in situ prepared superacid BF3-H 2O as an efficient promoter has been developed. The beneficial role of water in the reaction has been clarified with combination of control experiments and 11B NMR analysis. This reaction is a self-promoted model, which is triggered by the trace of water and continuously promoted by self released by-product water (or carboxylic acid). A wide range of substrates are investigated and the moderate to excellent yields and the good regioselectivities for secondary benzyl alcohols as well as arenes bearing electron-withdrawing groups have been achieved. As a result, moisture in the reaction system has been utilized as an efficient initiator in all benzylation cases.

Palladium-catalyzed desulfitative cross-coupling reaction of sodium sulfinates with benzyl chlorides

A palladium-catalyzed approach for the synthesis of diarylmethanes from sodium sulfinates and benzyl chlorides is described. Various aromatic sodium sulfinates were used as aryl sources via extrusion of SO2 and gave the diarylmethanes in moderate to good yields.

Synthesis of diarylmethane derivatives from Stille cross-coupling reactions of benzylic halides

A catalyst precursor prepared in situ from palladium acetate and a phosphine ligand was used for the Stille cross-coupling reaction of benzylic bromides and chlorides with aryltributyltin analogues. The reactions were performed at 80 °C using dppf as ligand in the presence of KF, or more conveniently using PPh3 in the absence of base, furnishing diarylmethane derivatives in high yields (86-99%). Using Pd(OAc)2/PPh3 as catalyst precursor competitive Stille and Suzuki cross-coupling reactions with benzyl chloride showed that in the absence of base or in the presence of KF the Stille product is the majority product, and only the Suzuki product was obtained in the presence of KOH as base.

A Study of N-Nitrosoamide-Mediated Friedel-Crafts Type Benzylation of Benzene-Toluene and Benzene-Anisole1a

Nitrogen-separated carbocation-carboxylate ion pairs were employed as sources of carbocations in the alkylation of aromatic compounds. The N-nitrosoamide approach to these nitrogenous-molecule-separated ion pairs is an excellent alternative to the standard acid-catalyzed Friedel-Crafts approach for studies of the alkylation because of the following variables: high reactivity of the electrophile, stability of the products, strict kinetic control, homogeneity, lack of over alkylation, straightforward chemistry, and good product balance. In deaminative benzylations of benzene-toluene and anisole-benzene mixtures, the values of kX/kB and % meta isomer are significantly different from those observed in the standard benzylations in a manner that indicates the deaminative electrophiles are more reactive than those generated by the standard Friedel-Crafts approach. The reactions show a direct proportionality between inter- and intramolecular selectivities and thus follow the Brown selectivity relationship (BSR). The benzylation of 2,4,6-trideuteriotoluene provided no evidence for deuterium rearrangements (or coupled benzyl rearrangements) in the arenium ion intermediate. Kinetic isotope effects were not detected. The methyl substituent on toluene appears to affect intermolecular selectivity (kT/kB) and intramolecular selectivity (o, m, p distribution) to similar degrees. A mechanism is proposed in which both selectivities are determined by activation energy differences in the transition states leading to the σ-complex intermediates. The observation that most standard Friedel-Crafts benzylations do not follow the BSR is discussed in terms of possible systematic errors in those cases. Silver ion-assisted Friedel-Crafts benzylations were performed under dry, basic conditions to investigate whether the standard approach could lead to data that obey the BSR.

A Study of Essentially Free Carbocations Derived via Diazonium and Oxo Diazonium Ions in the Liquid Phase

Nitrogen- and nitrous oxide-separated ion pairs containing 4-substituted benzyl cations and carboxylate or tosylate anions were prepared by thermolysis of N-nitroso- and N-nitroamides, acidification of phenyldiazomethane, and nitrosation of N-benzyl-O-benzoylhydroxylamine. The cations were generated in benzene/toluene and benzene/anisole mixtures and were found to partition between the counterion and the solvent and between the aromatic cosolvent and benzene. A familial relationship among the methods was observed. As the cation became more reactive, the yield of solvent-derived products (SDPs) rose and the ratio of rate constants for its reaction with toluene versus benzene, kT/kB, fell. The yield of SDP also rose as the temperature was decreased and as N2 was replaced by N2O; however, kT/kB remained unchanged. Inert diluents had no effect on kT/kB but decreased hydrocarbon yield by 40% on 2-fold dilution. In the presence of reactive diluents that are converted into secondary alkylating agents, both the % hydrocarbon and kT/kB rose. These results are interpreted in terms of the intermediacy of inert-molecule-separated ion pairs (IMSIPs) in deamination. The cation reacted with benzoates and tosylates not only at the oxygens but also at the ipso carbon; subsequent decarboxylation and desulfonylation, respectively, led to diphenylmethanes. The ester/SDP ratio is introduced as a new measure of carbocation reactivity.

Superacid-Catalyzed Reductive Friedel-Crafts Reaction of Arenes Using Arenecarbaldehyde Acetals

Reaction of 2-aryl-1,3-dioxane with arenes in the presence of a catalytic amount of trifluoromethane-sulfonic acid gave the corresponding diarylmethanes in good to excellent yields. The acid-catalyzed Friedel-Crafts benzylation of arenes could altenatively be carried out using arenecarbaldehyde and 1,3-propanediol. The reaction was assumed to proceed through a redox process involving hydride shift from the cyclic acetal moiety to the benzylic carbon. The hydride shift was confirmed by the reaction with 5-ethyl-2-phenyl-4,4,6,6-tetradeuterio-1,3-dioxane, wherein more than 90% deuterium was incorporated into the benzylic carbon of the diphenylmethane. Diphenylmethyl ether Ph2CHOCH2CH2CH2OH also reacted with benzene to afford diphenylmethane under the same reaction conditions, suggesting that the ether should be the plausible intermediate that underwent the hydride shift.