- β-Arylation of oxime ethers using diaryliodonium salts through activation of inert C(sp 3)-H bonds using a palladium catalyst
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An efficient method of selective β-arylation of oxime ethers was realized by using a palladium catalyst with diaryliodonium salts as the key arylation reagents. The reaction proceeded smoothly through the activation of inert C(sp3)-H bonds to give corresponding ketones and aldehydes. This convenient procedure can be successfully applied to construct new C(sp3)-C(sp2) bonds on a number of complex molecules derived from natural products and thus serves as a practical synthetic tool for direct late-stage C(sp3)-H functionalization.
- Peng, Jing,Chen, Chao,Xi, Chanjuan
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p. 1383 - 1387
(2016/02/05)
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- Proton-exchanged montmorillonite-mediated reactions of methoxybenzyl esters and ethers
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Proton-exchanged montmorillonite (H-mont) was found to be an eco-friendly and cost-effective catalyst for the generation of O-methylated quinone methides (QM) from the corresponding p or o-methoxybenzyl esters and ethers. Nucleophilic trapping of the O-methylated QM with arenes, alcohols, 1,3-dicarbonyl compounds, silyl enol ethers, and allylsilanes has been carried out, respectively, leading to eco-friendly benzylation reactions. Using this protocol, H-mont-mediated deprotection of PMB-protected esters and ethers have been realized for the first time. This work would pave the way for further exploration in O-alkylated QM that are of chemical and biological significance.
- Chen, Dongyin,Xu, Chang,Deng, Jie,Jiang, Chunhuan,Wen, Xiaoan,Kong, Lingyi,Zhang, Ji,Sun, Hongbin
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p. 1975 - 1983
(2014/03/21)
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- Palladium-catalyzed cross-coupling of cyclopropanol-derived ketone homoenolates with aryl bromides
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The cross-coupling reaction of cyclopropanol-derived ketone homoenolates bearing β-hydrogens with aryl and hetaryl bromides has been achieved for the first time. This reaction is high yielding, is broad in scope and uses a simple catalytic system. Notably, the proposed palladium homoenolates do not undergo β-hydride elimination to the corresponding α,β- unsaturated ketones.
- Rosa, David,Orellana, Arturo
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p. 5420 - 5422
(2013/06/27)
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- Trialkylsilyl triflimides as easily tunable organocatalysts for allylation and benzylation of silyl carbon nucleophiles with non-genotoxic reagents
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Trialkylsilyl triflimides generated in situ are unique catalysts for the electrophilic benzylation or allylation of trialkylsilylenol ethers or allyl trialkylsilanes with non-genotoxic alkylating reagents such as benzyl and allyl acetates. In most cases the reactions are fast at room temperature and yields are high. The reaction works particularly well with electron-rich benzyl donors including derivatives of pyrrole, indole and furane.
- Mendoza, Oscar,Rossey, Guy,Ghosez, Léon
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supporting information; experimental part
p. 2571 - 2575
(2010/06/21)
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- Enantioface-differentiating protonation with chiral γ-hydroxyselenoxides
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Enantioface-differentiating protonation of a chiral metal enolates of α-alkylcarbonyl compounds 7 has been developed using chiral γ-hydroxyselenoxides 1 as a proton source. Reaction of zinc bromide enolates of 2-benzyl- and 2-n-propylcyclohexanones with (S(Se))-1e gave (S)-2-benzylcyclohexanone 7a and (R)-2-n-propylcyclohexanone 7c in high enantiomeric excess, respectively. Intramolecular hydrogen bonding of the selenoxide 1, chelation effects between 1 and metal enolate, and 2-exo-hydroxy-10-bornyl-framework could contribute to this asymmetric induction.
- Takahashi, Tamiko,Nakao, Naoki,Koizumi, Toru
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p. 3293 - 3308
(2007/10/03)
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- Synthesis and structure-activity relationships of juvenoids derived from 2-(4-hydroxybenzyl)cycloalkan-1-ones
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Juvenoids 16-30, 32, 36, 38-41, 44-46, and 49-56 containing carbamate, carbonate, and urea moieties in the molecule were synthesized and subjected to a biological screening. Carbamate juvenoids 1-4 were used as reference compounds for a detailed structure-activity study of their analogues. A clear relationship between the nature of the side chain functional group and the biological activity was found. Surprisingly, not only the juvenoids 1,4 but also 38-41, the compounds with a reversed carbamate N,O-substitution pattern, showed very promising biological activity. In contrast, the carbonate and urea derivatives displayed a remarkably low activity. The relationship between the size and substitution at atoms C(2) and C(3) of the saturated ring and the biological activity is very complex and is still not completely understood.
- Rejzek,Wimmer,Saman,Ricankova,Nemec
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p. 1241 - 1255
(2007/10/02)
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- Use of dicobalt hexacarbonyl-estabilized propargyl cations in intramolecular Friedel-Crafts alkylations
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Cis-9a-ethynyl-1,2,3,4,4a,9a-hexahydro-9H-fluorenes and the corresponding dibenzofurans have been prepared by a stereoconvergent, intramolecular Friedel-Crafts alkylation involving dicobalt hexacarbonylstabilized carbocations.
- Grove, David D.,Miskevich, Frank,Smith, Chase C.,Corte, James R.
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p. 6277 - 6280
(2007/10/02)
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