- Template-Assisted meta-C?H Alkylation and Alkenylation of Arenes
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To expand the scope of meta-functionalization, a pyrimidine-based template effective for the formation of β-aryl aldehydes and ketones, using allyl alcohols, by meta-C?H activation of benzylsulfonyl esters is described. In addition, α,β-unsaturated aldehydes were generated by in situ olefination and deprotection of allyl benzyl ethers. These new functionalizations at the meta-position of an arene have also been successfully implemented in benzylphosphonate, phenethyl carbonyl, and phenethylsulfonyl ester scaffolds. Key to these successful new functionalizations is the creation of an electropositive palladium center by accepting the electron cloud from the metal to the energetically low-lying π-orbitals of pyrimidine ring, and it favors coordination of allyl alcohol to the metal center.
- Bag, Sukdev,Jayarajan, Ramasamy,Mondal, Rahul,Maiti, Debabrata
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Read Online
- Sulfated tungstate as hydroxyl group activator for preparation of benzyl, including p-methoxybenzyl ethers of alcohols and phenols
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Sulfated tungstate was found to be an effective heterogeneous and reusable catalyst for hydroxy group activation–mediated preparation of benzylic ethers including p-methoxybenzylic ethers of a wide range of alcohols and phenols under mild reaction conditions.
- Katkar, Kamlesh V.,Veer, Sachin D.,Akamanchi, Krishnacharya G.
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supporting information
p. 1893 - 1901
(2016/11/25)
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- Simple and efficient method for the protection of hydroxyl groups as 4-methoxybenzyl ethers
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PMB ethers of alcohols are obtained in good yields and under mild conditions using the 4-methoxybenzyl N-allyl thiocarbamate and N-bromosuccinimide (NBS)/TfOH as the catalyst. The present method is very fast, simple, and efficient. Copyright
- Kasprzycka, Anna,Ptaszek-Budniok, Agata,Szeja, Wies?aw
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supporting information
p. 2276 - 2284
(2014/07/07)
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- Selective synthesis of unsymmetrical ethers from different alcohols catalyzed by sodium bisulfite
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An efficient method for the preparation of unsymmetrical ethers from alcohols catalyzed by sodium bisulfite is reported. The procedure enables the direct dehydration of primary, secondary, and tertiary benzylic alcohols with aliphatic alcohols in the abse
- Yu, Jun-Lai,Wang, Hui,Zou, Kai-Feng,Zhang, Jia-Rui,Gao, Xiang,Zhang, Dan-Wei,Li, Zhan-Ting
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p. 310 - 315
(2013/01/15)
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- Vinyl polymerization versus [1,3] O to C rearrangement in the ruthenium-catalyzed reactions of vinyl ethers with hydrosilanes
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Two reactions, vinyl polymerization and [1,3] O to C rearrangement of vinyl ethers, are investigated in the ruthenium-catalyzed reaction with hydrosilanes. The reaction pathways are dependent on the substituents of the vinyl ether, in particular, those of the alkoxy group. Primary-, secondary-, and tertiary-alkyl vinyl ethers, ROCHCH2, are polymerized with ease to give the corresponding polymer in good yields. When R is electron-donating benzyl groups, the reaction does not give the polyvinyl ether but results in [1,3] O to C rearrangement to give the corresponding aldehyde, RCH2CHO in moderate to good yields. The rearrangement selectively proceeds when vinyl ethers having α-substituents are used as the starting materials to give the corresponding ketones in high yields. With catalytic amounts of hydrosilanes, the rearrangement gives ketones or aldehydes selectively. In sharp contrast, use of excess amounts of hydrosilanes leads to the rearrangement followed by reduction of the formed carbonyl group to give the corresponding silyl ethers in good yields. Nature of catalytically active species is discussed. Crown Copyright
- Harada, Nari-Aki,Nishikata, Takashi,Nagashima, Hideo
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supporting information; experimental part
p. 3243 - 3252
(2012/06/01)
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- A simple and an efficient indium trichloride catalyzed benzyl etherification
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An efficient method has been developed for the synthesis of benzyl ethers of alkyl, allyl and propargyl alchols by simple, direct coupling of alcohols in the presence of catalytic amount of L1C13 under solvent-free condition.
- Bhaskar,Solomon,Babu,Muralidharan,Perumal, Paramasivan T.
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scheme or table
p. 795 - 801
(2011/01/04)
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- Niobium(V) pentachloride: an efficient catalyst for C-, N-, O-, and S-nucleophilic substitution reactions of benzylic alcohols
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Benzylic alcohols undergo easy C-, N-, O-, and S- centered nucleophilic substitution reactions with a catalytic amount of NbCl5.
- Yadav,Bhunia, Dinesh C.,Vamshi Krishna,Srihari
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p. 8306 - 8310
(2008/03/30)
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- The synthesis of 5-hydroxy-3-methylnaphtho[2,3-c]furan-4,9-dione and 5,8-dihydroxy-1-methylnaphtho[2,3-c]furan-4,9-dione
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5-Hydroxy-3-methylnaphtho[2,3-c]furan-4,9-dione (1), a metabolite isolated from Aloe ferox and Bulbine capitata, has been synthesized by a sequence involving an annulation reaction between the anion of 4-methoxy-3-oxo-1,3-dihydroisobenzofuran-1-carbonitrile (8) and (E)-pent-3-en-2-one, followed by subsequent construction of the furan ring through allylic bromination, hydrolysis, and dehydration as the key steps. The formation of several unusual products observed in annulation reactions between (8) and O-protected derivatives of (E)-5-hydroxypent-3-en-2-one (9) can be rationalized by invoking the intermediacy of a reactive o-quinone methide. 5,8-Dihydroxy-1-methylnaphtho[2,3-c]furan-4,9-dione (2), another naturally occurring naphtho[2,3-c]furan-4,9-dione, has been prepared by a Friedel-Crafts acylation of 1,4-dimethoxybenzene with 2-methylfuran-3,4-dicarbonyl dichloride. Arguments are presented that 5,8-dihydroxynaphtho[2,3-c]furan-4,9-dione is a better structural representation than the alternative 4,9-dihydroxynaphtho[2,3-c]furan-5,8-dione tautomer in such systems, as the latter would contain a reactive isobenzofuran moiety.
- Piggott, Matthew J.,Wege, Dieter
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p. 691 - 702
(2007/10/03)
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- Chemoenzymatic Synthesis of the Microbial Elicitor (-)-Syringolide via a Fructose 1,6-Diphosphate Aldolase-Catalyzed Condensation Reaction
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Syringolide 2, an elicitor of the bacterial plant pathogen Pseudomonas syringae pv. tomato which triggers a hypersensitive defense response in resistant soybean plants, has been synthesized in five steps via a fructose 1,6-diphosphate aldolase reaction.
- Chenevert, Robert,Dasser, Mohammed
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p. 4529 - 4531
(2007/10/03)
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- Zeolite β-Induced Rearrangement of Alkoxybenzyl Allyl Ethers to Aldehydes and Ketones. 5.1 Variation of the Allylic Moiety
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Allylic PMB ethers rearranged in the presence of zeolite β to form 4-arylbutanals or 5-arylpentanones depending on the substituent pattern of the allylic moiety. Best results were obtained with substrates carrying simple substituents in the allylic 2-posi
- Wennerberg, Johan,Olofsson, Charlotte,Frejd, Torbjoern
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p. 3595 - 3598
(2007/10/03)
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- Synthetic studies towards carzinophilin: Synthesis and ammonium hydroxide-induced rearrangement of the epoxi-acid fragment
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An efficient synthesis of the epoxide-containing fragment 4 of carzinophilin has been completed. Intramolecular acyl transfer of a related epoxide afforded amide 16. Comparison by 1H NMR of 4 and 16 with authentic natural product provides further evidence for structural revision of carzinophilin.
- England, Pamela,Chun, Keun Ho,Moran, Edmund J.,Armstrong, Robert W.
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p. 2669 - 2672
(2007/10/02)
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