- Selective transition metal-free aroylation of diarylmethanes with 2-acyl-imidazolium salts via acyl C–C bond cleavage
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A highly chemoselective method is reported for the aroylation of simple diarylmethane derivatives via direct acyl C–C cleavage with 2-acyl-imidazolium salts under transition metal-free conditions. This represents a straightforward way to access a variety of sterically and electronically diverse 1,2,2-triarylethanones, a class of compounds with biological activities and various applications.
- Gan, Li-She,Li, Jie,Li, Lin-Lin,Wang, Jia-Min,Yang, Fan,Zou, Dong
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supporting information
(2020/11/13)
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- Construction of Di(hetero)arylmethanes Through Pd-Catalyzed Direct Dehydroxylative Cross-Coupling of Benzylic Alcohols and Aryl Boronic Acids Mediated by Sulfuryl Fluoride (SO2F2)
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A practical Pd-catalyzed direct dehydroxylative coupling of (hetero)benzylic alcohols with (hetero)arylboronic acids for the constructions of di(hetero)arylmethane derivatives under SO2F2 was described. This new method provided a strategically distinct approach to di(hetero)arylmethane derivatives from readily available and abundant benzylic alcohols under mild condition.
- Zhao, Chuang,Zha, Gao-Feng,Fang, Wan-Yin,Rakesh,Qin, Hua-Li
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p. 1801 - 1807
(2019/02/07)
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- Cross-Coupling of Phenol Derivatives with Umpolung Aldehydes Catalyzed by Nickel
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A nickel-catalyzed cross-coupling to construct the C(sp2)-C(sp3) bond was developed from two sustainable biomass-based feedstocks: phenol derivatives with umpolung aldehydes. This strategy features the in situ generation of moisture/air-stable hydrazones from naturally abundant aldehydes, which act as alkyl nucleophiles under catalysis to couple with readily available phenol derivatives. The avoidance of using both halides as the electrophiles and organometallic or organoboron reagents (also derived from halides) as the nucleophiles makes this method more sustainable. Water tolerance, great functional group (ketone, ester, free amine, amide, etc.) compatibility, and late-stage elaboration of complex biological molecules exemplified its practicability and unique chemoselectivity over organometallic reagents.
- Lv, Leiyang,Zhu, Dianhu,Tang, Jianting,Qiu, Zihang,Li, Chen-Chen,Gao, Jian,Li, Chao-Jun
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p. 4622 - 4627
(2018/05/22)
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- Palladium-Catalyzed Arylation of Benzylic C-H Bonds of Azaarylmethanes with Aryl Sulfides
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Benzylic C-H arylation of azaarylmethanes with aryl sulfides has been developed by using a Pd-NHC catalyst and an amide base. Various azaarylmethanes and aryl sulfides were involved in the reaction to afford the corresponding diarylmethanes in good to excellent yields. Moreover, triarylmethane synthesis was accomplished through iterative arylations of 2- or 4-methylpyridine with two different aryl sulfides.
- Gao, Ke,Yamamoto, Keita,Nogi, Keisuke,Yorimitsu, Hideki
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supporting information
p. 2956 - 2960
(2017/10/06)
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- Synthesis of Benzyltributylstannanes by the Reaction of N-Tosylhydrazones with Bu3SnH
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An efficient stannylation process with N-tosylhydrazones or directly with carbonyl compounds has been developed. A series of functionalized benzyl- and alkyltributylstannanes can be synthesized in moderate to good yields under transition-metal-free conditions. Tandem transformations involving stannylation/Stille cross-coupling reaction have been carried out without purification of the benzyltributylstannane intermediates to afford a series of diarylmethane derivatives.
- Qiu, Di,Wang, Shuai,Meng, He,Tang, Shengbo,Zhang, Yan,Wang, Jianbo
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p. 624 - 632
(2017/04/26)
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- Synthesis of Di- and Triarylmethanes through Palladium-Catalyzed Reductive Coupling of N -Tosylhydrazones and Aryl Bromides
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A palladium-catalyzed reductive coupling between N-tosylhydrazones and aryl bromides has been developed. The reaction provides an efficient method for the synthesis of diarylmethanes and triarylmethanes via the formation of C(sp2)-C(sp3) single bonds. This new methodology for the synthesis of diarylmethanes and triarylmethanes is featured by the ready availability of the starting materials, mild reaction conditions, and the tolerance of wide range of functional groups. The reaction follows a pathway including palladium carbene formation, migratory insertion, and reduction of the alkylpalladium(II) intermediate.
- Xia, Yamu,Hu, Fangdong,Xia, Ying,Liu, Zhenxing,Ye, Fei,Zhang, Yan,Wang, Jianbo
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p. 1073 - 1086
(2017/02/24)
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- Feedstocks to Pharmacophores: Cu-Catalyzed Oxidative Arylation of Inexpensive Alkylarenes Enabling Direct Access to Diarylalkanes
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A Cu-catalyzed method has been identified for selective oxidative arylation of benzylic C-H bonds with arylboronic esters. The resulting 1,1-diarylalkanes are accessed directly from inexpensive alkylarenes containing primary and secondary benzylic C-H bonds, such as toluene or ethylbenzene. All catalyst components are commercially available at low cost, and the arylboronic esters are either commercially available or easily accessible from the commercially available boronic acids. The potential utility of these methods in medicinal chemistry applications is highlighted.
- Vasilopoulos, Aristidis,Zultanski, Susan L.,Stahl, Shannon S.
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p. 7705 - 7708
(2017/06/20)
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- Au-complex containing phosphino and imidazolyl moieties as a bi-functional catalyst for one-pot synthesis of pyridine derivatives
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The complex of Au-L1 containing imidazolyl ring and the phosphine-ligated-Au moiety was synthesized and applied as the efficient bi-functional catalyst for the one-pot sequential condensation/annulation reaction for the synthesis of pyridine derivatives. It was found that, as for Au-L1, the involved imidazolyl group acted as a Lewis base to catalyze the condensation of carbonyl compounds with propargylamine to form the imino intermediate, and the involved Au+-complex species with alkynophilicity corresponded to the subsequent activation of imino-tailed alkynyl to afford dehydropyridine intermediate. The latter proceeded auto-oxidation reaction to afford the pyridine derivatives. The observed sequential catalysis over Au-L1 proved more efficient than that over the mechanical mixtures of the Au-complex (Au-L2) and N-methylimidazole, because the free N-methylimidazole as an N-containing donor competed with the alkyne substrate to coordinate to Au-center. Moreover, Au-L1 exhibited good generality to a wide range of the substrates for the synthesis of 2,3-fused pyridine derivatives and 2-aryl(heteroaryl)-substituted pyridines.
- Yang, Da,Liu, Huan,Wang, Dong-Liang,Lu, Yong,Zhao, Xiao-Li,Liu, Ye
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p. 323 - 330
(2016/09/23)
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- Alternative approach toward the generation of benzylic zinc reagent: Direct oxidative addition of active zinc into the carbon-oxygen bond of benzyl mesylates
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The use of highly active zinc, prepared by the Rieke method, for the direct preparation of benzylic zinc mesylate was investigated. The oxidative addition of highly active zinc to benzyl mesylate was easily completed under mild conditions. The resulting benzylic zinc mesylates were employed in subsequent cross-coupling reactions with a broad range of electrophiles, and the formation of the corresponding products was successful.
- Jung, Hye-Soo,Kim, Seung-Hoi
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p. 666 - 670
(2015/03/14)
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- Synthesis of 3-Arylpyridines via Palladium/Copper-Catalyzed Annulation of Allylamine/1,3-Propanediamine and Aldehydes
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A novel and efficient method for the synthesis of 3-arylpyridines from allylamine/propanediamine and aldehydes by palladium/copper-catalyzed oxidative tandem cyclization has been developed. With this reaction, a series of desired 3-arylpyridines was synthesized in moderate yields via C-C/C-N bond formation and 6-endo/exo-trig cyclization.
- Yang, Xiaodong,Yang, Shenghua,Xiang, Likui,Pang, Xiaobo,Chen, Baohua,Huang, Guosheng,Yan, Rulong
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p. 3732 - 3736
(2016/01/25)
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- Development of the direct Suzuki-Miyaura cross-coupling of primary B-alkyl MIDA-boronates and aryl bromides
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The development of a palladium-catalyzed sp3-sp2 Suzuki-Miyaura cross-coupling of B-alkyl-N-methyliminodiacetyl (B-alkyl MIDA) boronates and (hetero)aryl bromides is reported. This transformation is tolerant of a variety of functional groups (F, NO2, CN, Cl, COCH3, and CHO). B-Alkyl MIDA boronates allow an efficient cross-coupling reaction directed toward the synthesis of unsymmetrical methylene diaryls as well as alkylated arenes in good to excellent yields.
- St. Denis, Jeffrey D.,Scully, Conor C. G.,Lee, C. Frank,Yudin, Andrei K.
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supporting information
p. 1338 - 1341
(2014/04/03)
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- Iridium-promoted, palladium-catalyzed direct arylation of unactivated arenes
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A Pd-catalyzed cross-coupling reaction between Cp*(PMe 3)IrBn2 and aryl halides was developed. Examining the scope of this reaction led to the discovery that Cp*(PMe 3)IrMeCl activates C-H bonds on arene substrates that undergo subsequent Pd-catalyzed cross-coupling with aryl iodides. This Ir-promoted, Pd-catalyzed direct arylation is notable for its distal selectivity on substituted arenes lacking directing groups or a particular electronic bias.
- Durak, Landon J.,Lewis, Jared C.
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supporting information
p. 620 - 623
(2014/03/21)
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- Synthesis of heteroaryl compounds through cross-coupling reaction of aryl bromides or benzyl halides with thienyl and pyridyl aluminum reagents
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An efficient method for synthesis of useful biaryl building blocks containing 2-thienyl, 3-thienyl, 2-pyridyl, and 3-pyridyl moieties was provided through cross-coupling reactions of aryl bromides or benzyl halides with heteroaryl aluminum reagents in the presence of Pd(OAc)2 and (o-tolyl)3P. The coupling reaction also worked efficiently with heteroaryl bromides affording series of heterobiaryl compounds. The reaction of phenylbromide with in situ prepared 3-pyridyl aluminum was demonstrated to afford the product 8a in high yield. Additionally, the catalytic system was also suited well for the coupling reaction of benzyl halides with pyridyl aluminum reagents to afford series of pyridyl-arylmethane.
- Chen, Xu,Zhou, Lingmin,Li, Yimei,Xie, Tao,Zhou, Shuangliu
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p. 230 - 239
(2014/01/17)
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- Regioselectively functionalized pyridines from sustainable resources
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Make the most of it! An Ir-catalyzed dehydrogenative condensation of alcohols and 1,3-amino alcohol was used to construct pyridine derivatives regioselectively. This method provides access to unsymmetrically substituted pyridines and tolerates a wide variety of functional groups. Three equivalents of H2 are generated per pyridine unit formed and the alcohol substrates become completely deoxygenated. Copyright
- Michlik, Stefan,Kempe, Rhett
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supporting information
p. 6326 - 6329
(2013/07/05)
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- Preparation of functionalized organoindium reagents by means of magnesium insertion into organic halides in the presence of InCl3 at room temperature
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Magnesium, indium, palladium: An efficient one-pot procedure for the direct preparation of triorganoindium reagents from organic halides by means of magnesium insertion in the presence of InCl3 and LiCl is reported (see scheme). The organoindium reagents are obtained in good yields from functionalized aryl, heteroaryl, and alkyl bromides and benzyl chlorides at 25 °C in THF within 4h. Moreover, the resulting organoindium reagents could be efficiently used as reagents in Pd-catalyzed cross-coupling reactions with a wide functional group tolerance. Copyright
- Bernhardt, Sebastian,Shen, Zhi-Liang,Knochel, Paul
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supporting information
p. 828 - 833
(2013/02/23)
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- Palladium-catalyzed coupling reactions of (ArCH2)Ti(O-i-Pr) 3 with aromatic or heteroaromatic bromides
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Three benzyltitanium compounds of (ArCH2)Ti(O-i-Pr)3 (Ar = Ph (1a), 4-MeOC6H4 (1b), 4-FC6H 4 (1c)) were prepared and used as benzyl nucleophiles for coupling reactions with aromatic or heteroaromatic bromides. The simple catalytic system of 1 mol % Pd(OAc)2 and 2 mol % PCy3 worked efficiently for a wide variety of aromatic bromides, producing diarylmethanes in good to excellent yields of up to 96%. Coupling reactions of hindered aromatic bromides or aromatic bromides containing electron-withdrawing substituents were slower over longer reaction times of 3-6 h. Reactions of heteroaromatic bromides of bromopyridines, bromofurans, or bromothiophenes with benzyl reagents of 1a or 1b required either longer reaction times of 12-24 h or a higher reaction temperature of 80 °C, producing pyridyl-, furyl-, and thienyl-arylmethanes in moderate yields.
- Chang, Shu-Ting,Li, Qinghan,Chiang, Ruei-Tang,Gau, Han-Mou
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experimental part
p. 3956 - 3962
(2012/07/02)
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- The role of ion/neutral complexes in the fragmentation of N-benzyl-(alkylpyridinium) ions
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N-Benzylpyridinium ions bearing an alkyl group at the pyridine nucleus were studied as potential precursors of gaseous ion/neutral complexes. The occurrence of I/N complexes [C6H5CH2 + ? alkylpyridine] was probed by the reactivity of the potential benzylic hydride donor sites present in the ortho-, meta- and para-alkyl groups (R = methyl, ethyl, isopropyl and benzyl). Collision-induced dissociation of the ions, carried out in an electrical ion cage mass spectrometer, revealed that hydride transfer strongly depends both on the energy requirements of the hydride transfer but also on the position of the hydride donor. Hydride transfer, giving rise to the loss of toluene, was found to occur exclusively with those N-benzylpyridinium ions which bear an isopropyl or a benzyl substituent in the ortho position of the pyridine ring, thus reflecting the intermediacy of I/N complexes. All of the putative hydride donor alkyl groups were found to be non-reactive in the meta and para positions, as were methyl and ethyl groups even in the ortho positions. Density functional calculations (B3LYP/6-311+G/3d,2p)//(B3LYP/6-31+G(d)) on the hydride-transfer and simple-cleavage channels were carried out to help rationalizing these observations. The results suggest that the intra-complex hydride abstraction from the 3- and 4-isopropyl- and from the 3- and 4-benzylpyridine neutrals, although being thermodynamically favorable, is suppressed by substantial intra-complex rotational (or reorientation) barriers.
- Kuck, Dietmar,Grützmacher, Hans-Friedrich,Barth, Dieter,Heitkamp, Sandra,Letzel, Matthias C.
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body text
p. 159 - 166
(2012/07/13)
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- Affinity of 3-acyl substituted 4-quinolones at the benzodiazepine site of GABAA receptors
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The finding that alkyl 1,4-dihydro-4-oxoquinoline-3-carboxylate and N-alkyl-1,4-dihydro-4-oxoquinoline-3-carboxamide derivatives may be high-affinity ligands at the benzodiazepine binding site of the GABAA receptor, prompted a study of 3-acyl-1,4-dihydro-4-oxoquinoline (3-acyl-4-quinolones). In general, the affinity of the 3-acyl derivatives was found to be comparable with the 3-carboxylate and the 3-carboxamide derivatives, and certain substituents (e.g., benzyl) in position 6 were again shown to be important. As it is believed that the benzodiazepine binding site is situated between an α- and a γ-subunit in the GABAA receptor, selected compounds were tested on the α1β2γ2s, α2β2γ2s and α3β2γ2s GABAA receptor subtypes. The 3-acyl-4-quinolones display various degrees of selectivity for α1- versus α2- and α3-containing receptors, and high-affinity ligands essentially selective for α1 over α3 were developed.
- Lager, Erik,Nilsson, Jakob,stergaard Nielsen, Elsebet,Nielsen, Mogens,Liljefors, Tommy,Sterner, Olov
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p. 6936 - 6948
(2008/12/21)
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- One-pot dual substitutions of bromobenzyl chloride, 2-chloromethyl-6- halogenoimidazo[1,2-a]pyridine and -[1,2-b]pyridazine by Suzuki-Miyaura cross-coupling reactions
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A very simple, mild and inexpensive palladium-catalyzed cross-coupling of (hetero)arylboronic acids with benzylic halides occurs in good yield. This method was successfully expanded to two heterocyclic electrophiles and allowed onepot dual substitutions of bromobenzyl chloride, 2-chloromethyl-6- halogenoimidazo[1,2-a]pyridine or -[1,2-b]pyridazine, leading to numerous new unsymmetrical methylenelinked biaryl systems. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Henry, Nicolas,Enguehard-Gueiffier, Cecile,Thery, Isabelle,Gueiffier, Alain
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supporting information; experimental part
p. 4824 - 4827
(2009/05/07)
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- Suzuki-Miyaura coupling of benzylic carbonates with heteroarylboronic acids
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Cross-coupling of benzylic carbonates with heteroarylboronic acids successfully proceeded in the presence of the palladium catalyst that was generated in situ from [Pd(rf-C3Hs)CI]2 and a chelate bisphosphine DPPPent. Various heteroarylboronic acids were applicable to the catalytic cross-coupling, giving the desired benzylated heteroaromatics in high yields.
- Kuwano, Ryoichi,Yu, Jung-Yi
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p. 233 - 237
(2008/09/17)
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- Cross-coupling reaction of allylic and benzylic carbonates with organo[2-(hydroxymethyl)phenyl]dimethylsilanes
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The title reaction is found to proceed in the presence of a palladium catalyst and in the absence of any activator. Various functional groups are tolerated to give a diverse range of 1,4-diene and diarylmethane products, which are ubiquitous units of natural products and pharmaceuticals. Copyright
- Nakao, Yoshiaki,Ebata, Shiro,Chen, Jinshui,Imanaka, Hidekazu,Hiyama, Tamejiro
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p. 606 - 607
(2008/02/07)
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- Suzuki-miyaura cross-coupling reactions of benzyl halides with potassium aryltrifluoroborates
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(Chemical Equation Presented) The palladium-catalyzed cross-coupling of potassium aryltrifluoroborates with benzylic halides occurs in good yield with high functional group tolerance. The increased stability of potassium aryltrifluoroborates compared to other boron coupling partners makes this an effective route to functionalized methylene-linked biaryl systems.
- Molander, Gary A.,Elia, Maxwell D.
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p. 9198 - 9202
(2007/10/03)
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- Cobalt-catalyzed cross-coupling reaction of chloropyridines with grignard reagents
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Treatment of 2-chloropyridine with benzylmagnesium chloride in the presence of a catalytic amount of cobalt(II) acetylacetonate in dioxane afforded the corresponding cross-coupling product in excellent yield. Trimethylsilylmethyl and phenyl Grignard reagents also participated in similar cross-coupling reactions.
- Ohmiya, Hirohisa,Yorimitsu, Hideki,Oshima, Koichiro
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p. 1240 - 1241
(2007/10/03)
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- Sequential amination/annulation/aromatization reaction of carbonyl compounds and propargylamine: A new one-pot approach to functionalized pyridines
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A general one-pot synthesis of pyridines 4a-t from the reaction of dialkyl acyclic/cyclic ketones 1a-i, methyl, aryl/heteroaryl ketones 1m-r, and aldehydes bearing α-hydrogens 1s,t with propargylamine 2 is described. Gold and copper salts are efficient catalysts for the reaction of ketones with 2. The formation of the pyridines 4 is suggested to proceed through the sequential amination of carbonyl compounds followed by regioselective 6-endo-dig cyclization of the N-propargylenamine (N-propargyldienamine) intermediate 3(5) and aromatization reaction. Whereas the preparation of linear polycyclic pyridine 4i can be carried out by reacting cholestan-3-one 1i with 2, the angular polycyclic pyridine 4j has been obtained starting from cholest-5-en-3-one 1j. Selectivity of the reaction of polycyclic dicarbonyls 1k,1 with 2 has also been investigated.
- Abbiati, Giorgio,Arcadi, Antonio,Bianchi, Gabriele,Di Giuseppe, Sabrina,Marinelli, Fabio,Rossi, Elisabetta
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p. 6959 - 6966
(2007/10/03)
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- Extended scope of in situ iodotrimethylsilane mediated selective reduction of benzylic alcohols
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Iodotrimethylsilane, generated in situ from chlorotrimethylsilane and sodium iodide in acetonitrile, selectively reduces moderately electron deficient benzylic alcohols to the analogous toluenes; other reduction sensitive functional groups such as ketone, aldehyde, nitrile, and nitro are unaffected.
- Cain,Holler
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p. 1168 - 1169
(2007/10/03)
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- A novel reduction of pyridinemethanols by samarium diiodide
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An efficient synthesis of alkylpyridine derivatives by SmI2 mediated deoxygenation of pyridinemethanol derivatives is described.
- Kato, Yoshiaki,Mase, Toshiaki
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p. 8823 - 8826
(2007/10/03)
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- SYNTHESIS OF 2- AND 4-BENZYLPYRIDINES - REAGENTS FOR DETECTION OF TOXIC CHEMICALS
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Synthesis and isolation of 2- and 4-benzylpyridines, which are used in thin-layer chromatography for detection of toxic chemicals in the environment, have been described.Synthesis of 2- and 4-benzylpyridines is based on homolytic benzylation of pyridine with toluene in the presence of trifluoroacetic acid.
- Ivanova, L. P.,Kasatkina, A. A.,Trifonova, V. N.
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p. 1981 - 1982
(2007/10/02)
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- REDUCTION OF ALDEHYDES AND KETONES TO METHYLENE DERIVATIVES USING AMMONIUM FORMATE AS A CATALYTIC HYDROGEN TRANSFER AGENT
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Various aromatic aldehydes and ketones were reduced to the corresponding hydrocarbons using ammonium formate as the hydrogen source.
- Ram, Siya,Spicer, Leonard D.
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p. 3741 - 3744
(2007/10/02)
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- Z,E-ISOMERS OF 10,10-DIMETHYL-9-BENZYLIDENE-9,10-DIHYDRO-10-SILA-2-AZAANTHRACENE AND REACTIONS OF 10,10-DIMETHYL-9,10-DIHYDRO-10-SILA-2-AZAANTHRACENE UNDER CONDITIONS OF BASIC CATALYSIS
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The synthesis of 9-benzylidenesilaazaanthracenes has been achieved, and the configurations of their Z- and E-isomers have been established.The reactions of silaazaanthracene in the presence of aromatic aldehydes and bases have been studied; these result in dimerization, oxidation, cleavage of the Si-C bond, and desilylation of the heterocyclic system.
- Prostatkov, N. S.,Varlamov, A. V.,Kozm, Kossuo,Aliev, A. E.,Fomichev, A. A.
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p. 1136 - 1140
(2007/10/02)
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- Reactions of 1,4-Bis(trimethylsilyl)-1,4-dihydropyridines with Carbonyl Compounds: A New Method for Regioselective Synthesis of 3-Alkylpyridines
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A new method for the alkyl group introduction at the 3-position of pyridines is described: Reductive disilylation of pyridine, its 2-methyl, 3-methyl, and 4-methyl derivatives affords the corresponding 1,4-disilyl-1,4-dihydropyridines.Tn the presence of a catalytic amount of tetrabutylammonium fluoride, these dihydropyridines smoothly react with a variety of aldehydes and ketones to give 3-alkylpyridines.
- Tsuge, Otohiko,Kanemasa, Shuji,Naritomi, Toshio,Tanaka, Junji
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p. 1497 - 1504
(2007/10/02)
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- REGIOSELECTIVE ALKYL GROUP INTRODUCTION AT THE 3-POSITION OF PYRIDINE VIA 1,4-BIS(TRIMETHYLSILYL)-1,4-DIHYDROPYRIDINE
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The reaction of 1,4-bis(trimethylsilyl)-1,4-dihydropyridine with aldehydes and ketones in the presence of tetrabutylammonium fluoride offers a convenient method for the preparation of 3-alkylpyridines.
- Tsuge, Otohiko,Kanemasa, Shuji,Naritomi, Toshio,Tanaka, Junji
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p. 1255 - 1258
(2007/10/02)
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