- 2,2'-Dimethoxybibenzyl
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The 2,2'-dimethoxybibenzyl molecule, C16H18O2, has the midpoint of the -CH2-CH2- bond on an inversion centre.Each benzene ring deviates slightly from planarity, shows marked angular distortion and is inclined at 81.5(1) deg to the plane of the C(Ar)-CH2-CH2-moiety.
- Ross, Jennifer-Nicola,Wardell, James,Ferguson, George,Low, John N.
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- Synthesis of Dibenzyls by Nickel-Catalyzed Homocoupling of Benzyl Alcohols
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Dibenzyls are essential building blocks that are widely used in organic synthesis, and they are typically prepared by the homocoupling of halides, organometallics, and ethers. Herein, we report an approach to this class of compounds using alcohols, which are more stable and readily available. The reaction proceeds via nickel-catalyzed and dimethyl oxalate assisted dynamic kinetic homocoupling of benzyl alcohols. Both primary and secondary alcohols are tolerated.
- Pan, Feng-Feng,Guo, Peng,Huang, Xiaochuang,Shu, Xing-Zhong
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p. 3094 - 3100
(2021/04/23)
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- A Bisphenolic Honokiol Analog Outcompetes Oral Antimicrobial Agent Cetylpyridinium Chloride via a Membrane-Associated Mechanism
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Targeting Streptococcus mutans is the primary focus in reducing dental caries, one of the most common maladies in the world. Previously, our groups discovered a potent bactericidal biaryl compound that was inspired by the natural product honokiol. Herein, a structure activity relationship (SAR) study to ascertain structural motifs key to inhibition is outlined. Furthermore, mechanism studies show that bacterial membrane disruption is central to the bacterial growth inhibition. During this process, it was discovered that analog C2 demonstrated a 4-fold better therapeutic index compared to the commercially available antimicrobial cetylpyridinium chloride (CPC) making it a viable alternative for oral care.
- Ochoa, Cristian,Solinski, Amy E.,Nowlan, Marcus,Dekarske, Madeline M.,Wuest, William M.,Kozlowski, Marisa C.
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- Ni-Catalyzed Iterative Alkyl Transfer from Nitrogen Enabled by the in Situ Methylation of Tertiary Amines
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Current methods to achieve transition-metal-catalyzed alkyl carbon-nitrogen (C-N) bond cleavage require the preformation of ammonium, pyridinium, or sulfonamide derivatives from the corresponding alkyl amines. These activated substrates permit C-N bond cleavage, and their resultant intermediates can be intercepted to affect carbon-carbon bond-forming transforms. Here, we report the combination of in situ amine methylation and Ni-catalyzed benzalkyl C-N bond cleavage under reductive conditions. This method permits iterative alkyl group transfer from tertiary amines and demonstrates a deaminative strategy for the construction of Csp3-Csp3 bonds. We demonstrate PO(OMe)3 (trimethylphosphate) to be a Ni-compatible methylation reagent for the in situ conversion of trialkyl amines into tetraalkylammonium salts. Single, double, and triple benzalkyl group transfers can all be achieved from the appropriately substituted tertiary amines. Transformations developed herein proceed via recurring events: The in situ methylation of tertiary amines by PO(OMe)3, Ni-catalyzed C-N bond cleavage, and concurrent Csp3-Csp3 bond formation.
- Nwachukwu, Chideraa Iheanyi,McFadden, Timothy Patrick,Roberts, Andrew George
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p. 9979 - 9992
(2020/09/03)
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- Nickel catalyzed deoxygenative cross-coupling of benzyl alcohols with aryl-bromides
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A nickel-catalyzed cross-electrophile coupling of benzyl alcohols with aromatic bromides has been developed. This deoxygenative cross-coupling occurs under mild reaction conditions at ambient temperature affording diarylmethanes, or 1,3-diarylpropenes from benzyl allyl alcohols. The system demonstrated good chemoselectivity tolerating an assortment of reactive functional groups.
- Kumar Chenniappan, Vinoth,Peck, Devin,Rahaim, Ronald
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supporting information
(2020/03/03)
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- Methoxy-substituted α, n-didehydrotoluenes. photochemical generation and polar vs diradical reactivity
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The photoreactivity of differently substituted (chloromethoxybenzyl)trimethylsilanes in alcohols and alcohol/water mixtures has been investigated by means of a combined computational and experimental approach. Subsequent elimination of the chloride anion and the trimethylsilyl cation gives the corresponding methoxy-substituted α,n-didehydrotoluenes (α,n-MeO-DHTs). The rate of desilylation is evaluated through the competition with arylation via phenyl cation (ca. 108s-1). α,2-MeO- and α,4-MeO-DHTs show a purely radical behavior (H abstraction from the solvent, methanol), while α,3-MeO-DHT shows mainly a ionic chemistry, as when the parent α,3-DHT is thermally generated. This is likely due to triplet-singlet surfaces crossing occurring during desilylation.
- Raviola, Carlotta,Ravelli, Davide,Protti, Stefano,Fagnoni, Maurizio
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supporting information
p. 13874 - 13881
(2015/02/05)
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- Catalytic double C-Cl bond activation in CHlby iron(III) salts with grignard reagents
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Cross-coupling of Grignard reagents with dichloromethane is achieved using iron(III) catalysts. Aryl- and benzylmagnesium bromides show a range of activity toward double C-Cl bond activation resulting in the insertion of methylene fragments between two equivalents of the nucleophilic partner. Georg Thieme Verlag Stuttgart.
- Qian, Xin,Kozak, Christopher M.
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experimental part
p. 852 - 856
(2011/06/21)
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- Raney Ni-Al alloy-mediated reduction of benzils in wate
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Raney Ni-Al alloy in a dilute aqueous alkaline solution has been shown to be a powerful reducing agent and is highly effective for the reduction of alkylbenzils and alkoxybenzils to afford the corresponding 1,2-diarylethers at 90°C, in the absence of organic solvents. 4,4'-Dinitrobenzil was transformed selectively to 1,2-bis(4-aminophenyl) ethane.
- Liu, Guo-Bin,Zhao, Hong-Yun,Dai, Lu,Thiemann, Thies,Tashiro, Hideki,Tashiro, Masashi
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experimental part
p. 579 - 581
(2010/02/28)
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- Reductive metalation of 1,2-diaryl-substituted ethenes: Synthetic applications
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Reduction of 1,2-diaryl-substituted ethenes with Na metal in dry THF allowed easy access to a variety of 1,2-diaryl-1,2-disodiumethanes. These diorganometallic intermediates were elaborated into the corresponding 1,2-diarylethanes (aqueous work up), or cycloalkylated with 1,3- dichloropropanes. The last reaction led to a highly diastereoselective synthesis of trans-1,2-diaryl-substituted cyclopentanes.
- Azzena, Ugo,Dettori, Giovanna,Lubinu, Caterina,Mannu, Alberto,Pisano, Luisa
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p. 8663 - 8668
(2007/10/03)
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- Palladium-catalyzed homocoupling reactions between two Csp3-Csp3 centers
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(Matrix Presented) A novel palladium-catalyzed coupling reaction between two Csp3-Csp3 centers has been investigated. This protocol is initiated by the oxidative addition of an α-halo carbonyl compound to a palladium(0) species, followed by the double transmetalation. The key dialkyl palladium intermediate undergoes reductive elimination to form the desired coupling product.
- Lei, Aiwen,Zhang, Xumu
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p. 2285 - 2288
(2007/10/03)
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- REDUCTIVE COUPLING OF BENZOIC ACID HALIDES AND ESTERS USING LOW-VALENT TITANIUM
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The reductive coupling of (substituted) benzoic acid chlorides and esters is achieved using low-valent titanium, generated from TiCl3 and LiAlH4.Both acid chlorides and esters seem to follow the same two reaction pathways: one path via tolanes to stilbenes, the other via benzils to complex mixtures of products arising from reduction and further coupling reactions.Although the exact product balance depends upon the reaction conditions the major product is (substituted) cis-stilbene.
- Dang, Y.,Geise, H. J.
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p. 375 - 380
(2007/10/02)
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- REDUCTIVE COUPLING OF BENZYL HALIDES USING NICKEL(0)-COMPLEX GENERATED IN SITU IN THE PRESENCE OF TETRAETHYLAMMONIUM IODIDE, A SIMPLE AND CONVENIENT SYNTHESIS OF BIBENZYLS
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Zerovalent nickel complex generated in situ by reduction of NiBr2(PPh3)2 with zinc powder in the presence of Et4NI was found to be an effective catalyst for homo-coupling of benzyl halides.The catalytic reactions proceeded smoothly in various solvents under mild conditions to afford dehalogenative-coupling products in good to high yields.
- Iyoda, Masahiko,Sakaitani, Masahiro,Otsuka, Hiroki,Oda, Masaji
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p. 127 - 130
(2007/10/02)
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- Photochemistry of α-Aryl Carboxylic Anhydrides. Part 4. Photoreactions of Some Asymmetrical Anhydrides derived from o- and p-Methoxyphenylacetic Acid, and of Some of the Phenylacetate Ester Photoproducts
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Irradiation of the two asymmetrical carboxylic anhydrides R1C6H4CH2.CO.O.CO.CH2C6H5 (1a and 1b) at 254 nm in acetonitrile leads to the formation of esters and bibenzyls.Among the esters produced, the asymmetrical ones with structure R1C6H4CH2.O(C=O)CH2C6H5 are the most abundant.These are for the greater part formed intramolecularly by decarbonylation of one excited anhydride molecule.This result is in line with a mechanism involving electron transfer after excitation of the anhydride molecule.The bibenzyls are formed by the recombination of benzyl radicals.In the initial stage of the reaction of the anhydrides, the three bibenzyls are formed with the asymmetrical one predominating .In the later stages, when substantial amounts of esters are present, the formation of the bibenzyls also originates in part from the photodecomposition of the esters.The photochemistry of the various (symmetrical and asymmetrical) esters which are photoproducts from the anhydrides (1a and b) has also been studied.The symmetrical esters (2a and b) afforded quantitatively the bibenzyls (3a and b), respectively.The asymmetrical esters gave variable yields of the three (possible) bibenzyls, depending on the type of ester considered.For the asymmetrical esters for which bibenzyl formation could be quenched by (Z)-piperylene, the three bibenzyls were formed in a close to statistical ratio, e.g. (2c) yielded the bibenzyls (3a, c, and e) in a ratio of 1:2.5:1.With the esters for which the photodecarboxylation was not quenchable by (Z)-piperylene, a relatively higher yield of the asymmetrical bibenzyl was found, e.g. (2d) yielded the bibenzyls (3b, d, and e) in a ratio of 1:6:1.These results are rationalized in terms of a recombination of free radicals resulting from the triplet excited esters after spin inversion in the former case, and a recombination of a radical pair in the solvent cage resulting from the singlet excited or shortlived triplet excited ester in the latter case.
- Roof, Antonius A. M.,Woerden, Hendrik F. van,Cerfontain, Hans
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p. 838 - 841
(2007/10/02)
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