- MOF-808 as a recyclable catalyst for the photothermal acetalization of aromatic aldehydes
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Metal-organic frameworks (MOFs) show promise for catalysis applications due to their porosity, high internal surface area, and structural adaptability. Typical acetylation reactions of aldehydes require elevated temperatures and excess alcohol to drive the reactions to completion. In this current work, MOF-808 is used as a heterogeneous catalyst for acetylation of aldehydes in methanol using a mild photothermal process. Optimized conditions gave 72% yield of 2-(dimethoxymethyl)naphthalene in the presence of 10 mol% MOF-808 at 45 °C using only a fluorescent lamp. MOF-808 can be recycled up to 5 times with no loss in catalytic activity. A proof-of-principle substrate scope demonstrates the potential utility for aromatic and aliphatic substrates.
- Rabon, Allison M.,Doremus, Jared G.,Young, Michael C.
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supporting information
(2021/04/02)
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- Formation of Acetals and Ketals from Carbonyl Compounds: A New and Highly Efficient Method Inspired by Cationic Palladium
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The development of a new, highly efficient, and simple method for masking carbonyl groups as acetals and ketals is described. This methodology relies on the nature of the palladium catalyst to direct the acetalization/ketalization reaction. This new protocol is mild and proceed with a very low catalyst loading at ambient temperatures. The method has been extended to a wide variety of different carbonyl compounds with various steric encumbrances to form the corresponding acetals and ketals in excellent yields.
- Green, Shawn D.,Kindoll, Tyler,Lazaro-Martinez, Brenda,Mensah, Enoch A.,West, Jesse
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p. 1810 - 1814
(2019/09/09)
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- House bulb light-induced photochemical acetalization of carbonyl compounds catalyzed by Eosin Y
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We have systematically studied the reactions of acetalization and found that high reaction efficiency can be achieved using cheap and readily available organic Eosin Y as catalyst. The reaction proceeds smoothly under house bulbs and shows excellent functional group tolerance. The substrates of the reaction system are compatible with aromatic aldehydes, aliphatic aldehydes, aromatic ketones, and cyclic ketones with high yields.
- Zhou, Quan,Jia, Tao,Li, Xiao-Xuan,Zhou, Lin,Li, Chang-Jiang,Feng, Yi-Si
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supporting information
p. 1068 - 1075
(2018/05/23)
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- Silver-Catalyzed Olefination of Acetals and Ketals with Diazoesters to β-Alkoxyacrylates
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The first silver-catalyzed reaction of acetals or ketals with diazoesters leading to trisubstituted or tetrasubstituted β-alkoxyacrylates is now reported. A broad range of acetals and ketals bearing different substituents is compatible with this protocol and thus provides an attractive approach for the synthesis of complex β-alkoxyacrylates. The power of this method was further demonstrated by the successful synthesis of picoxystrobin, which is one of the most popular agricultural fungicides commercialized by Dupont.
- Li, Jiawen,Qian, Bo,Huang, Hanmin
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supporting information
p. 7090 - 7094
(2018/11/23)
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- Synthesis of unnatural α-amino esters using ethyl nitroacetate and condensation or cycloaddition reactions
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We report here on the use of ethyl nitroacetate as a glycine template to produce α-amino esters. This started with a study of its condensation with various arylacetals to give ethyl 3-aryl-2-nitroacrylates followed by a reduction (NaBH4 and then zinc/HCl) into α-amino esters. The scope of this method was explored as well as an alternative with arylacylals instead. We also focused on various [2 + 3] cycloadditions, one leading to a spiroacetal, which led to the undesired ethyl 5-(benzamidomethyl)isoxazole-3-carboxylate. The addition of ethyl nitroacetate on a 5-methylene-4,5-dihydrooxazole using cerium(IV) ammonium nitrate was also explored and the synthesis of other oxazole-bearing α-amino esters was achieved using gold(I) chemistry.
- Gagnot, Glwadys,Hervin, Vincent,Coutant, Eloi P.,Desmons, Sarah,Baatallah, Racha,Monnot, Victor,Janin, Yves L.
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supporting information
p. 2846 - 2852
(2018/11/27)
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- Direct Asymmetric Friedel-Crafts Reaction of Naphthols with Acetals Catalyzed by Chiral Bronsted Acids
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The Friedel-Crafts method synthesis of chiral ethers from various acetals and naphthols catalyzed by chiral Bronsted acids with acetic acid as an effective additive is described. We found that the chiral phosphoric acid (R)-TRIP could efficiently catalyze the asymmetric Friedel-Crafts reaction of naphthols with acetals affording chiral ethers in good enantioselectivity and yield.
- Qin, Long,Wang, Pei,Zhang, Yixin,Ren, Zhengxiang,Zhang, Xin,Da, Chao-Shan
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supporting information
p. 571 - 574
(2016/03/01)
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- Dialkyl Ether Formation by Nickel-Catalyzed Cross-Coupling of Acetals and Aryl Iodides
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A new substrate class for nickel-catalyzed C(sp3) cross-coupling reactions is reported. α-Oxy radicals generated from benzylic acetals, TMSCl, and a mild reductant can participate in chemoselective cross-coupling with aryl iodides using a 2,6-bis(N-pyrazolyl)pyridine (bpp)/Ni catalyst. The mild, base-free conditions are tolerant of a variety of functional groups on both partners, thus representing an attractive C-C bond-forming approach to dialkyl ether synthesis. Characterization of a [(bpp)NiCl] complex relevant to the proposed catalytic cycle is also described.
- Arendt, Kevin M.,Doyle, Abigail G.
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supporting information
p. 9876 - 9880
(2015/08/19)
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- Efficient enantioselective synthesis of dihydropyrans using a chiral N, N ′-dioxide as organocatalyst
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The bifunctional organocatalyst C3 N,N′-dioxide has been successfully applied to the asymmetric cascade Michael/hemiacetalization reaction of α-substituted cyano ketones and β,γ-unsaturated α-ketoesters for the synthesis of multifunctionalized chiral dihydropyrans. The corresponding products were obtained in excellent yields (up to 99%) with high to excellent enantioselectivities (up to 99% ee).
- Feng, Juhua,Fu, Xuan,Chen, Zhenling,Lin, Lili,Liu, Xiaohua,Feng, Xiaoming
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supporting information
p. 2640 - 2643
(2013/07/19)
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- An alternative approach to direct aldol reaction based on gold-catalyzed methoxyl transfer
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A mild and catalyzed alternative to the direct aldol reaction has been developed based on the gold-catalyzed methoxy group transfer from dimethyl acetals to terminal alkynes. Due to the simultaneous activation of the acetals, this aldol approach is only functional for acetals but not aldehydes. A ligand effect from the gold complex has also been observed. Copyright
- Zhang, Moran,Wang, Yunxia,Yang, Yang,Hu, Xiangdong
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supporting information; experimental part
p. 981 - 985
(2012/06/30)
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- Gold-catalyzed intermolecular carboalkoxylation of alkenes
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A gold-catalyzed intermolecular carboalkoxylation of alkenes has been developed. Readily available and inexpensive dimethyl acetals have been employed as a facile reagent to achieve the carboalkoxylation of alkenes. Copyright
- Dong, Wenmin,Zhang, Moran,Xiao, Fenfen,Wang, Yunxia,Liu, Wu,Hu, Xiangdong,Yuan, Qiang,Zhang, Shaofei
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supporting information
p. 2799 - 2802
(2013/02/22)
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- Mesoporous aluminosilicate-catalyzed allylation of carbonyl compounds and acetals
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A mesoporous aluminosilicate (Al-MCM-41) was found to be an effective heterogeneous catalyst for the reaction of both carbonyl compounds and acetals with allylsilanes to afford the corresponding homoallyl silyl ethers and homoallyl alkyl ethers, respectively. Both the mesoporous structure and the presence of aluminum moiety were indispensable for the high catalytic activity of Al-MCM-41. Moreover, Al-MCM-41 could catalyze the reaction of acetals chemoselectively in the presence of the corresponding carbonyl compounds. The solid acid catalyst Al-MCM-41 could be recovered easily by filtration and could be reused three times without a significant loss of catalytic activity.
- Ito, Suguru,Hayashi, Akira,Komai, Hirotomo,Yamaguchi, Hitoshi,Kubota, Yoshihiro,Asami, Masatoshi
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supporting information; experimental part
p. 2081 - 2089
(2011/04/19)
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- Regioselectivity in arene-catalyzed reductive lithiation of acetals of chlorobenzaldehydes
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The regioselectivity of arene-catalyzed reductive lithiation of acetals of chlorobenzaldehydes strongly depends on the form of lithium metal employed as a reducing agent. According to previous findings, naphthalene catalyzed reductions run in the presence of lithium powder (high Na content) led to competitive metalations of both aromatic carbon-chlorine and benzylic carbon-oxygen bonds. At variance with these results, naphthalene catalyzed reductions run in the presence of lithium wire (either high or low Na content) led to highly regioselective metalation of aromatic carbon-chlorine bonds. These results disclose new possibilities of selective applications of arene-catalyzed reductive lithiation reactions.
- Azzena, Ugo,Dettori, Giovanna,Sforazzini, Giuseppe,Yus, Miguel,Foubelo, Francisco
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p. 1557 - 1563
(2007/10/03)
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- Ce(3+)-Exchanged Montmorillonite (Ce(3+)-Mont) as a Useful Substrate-Selective Acetalization Catalyst
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The acetalization of carbonyl compounds with methanol was investigated in the presence of a cation-exchanged montmorillonite (M(n+)-mont; M(n+) = Ce(3+), Zr(4+), Fe(3+), Al(3+), Zn(2+), H(+) and Na(1+).Ce(3+)-mont was found to be the most effective catalyst for substrate-selective acetalization.Cyclohexanones, benzaldehydes, and acid-sensitive 2-furancarboxaldehyde were converted nearly quantitatively to the corresponding acetals in methanol at 25 deg C in the presence of Ce(3+)-mont.The substrates were activated by a Lewis acidic Ce(3+) cation in the interlayer space on the order of 1 kJ mol-1 as measured by FT-IR.The turnover number was estimated to be up to 2.6E3 based on the number of active acid sites in Ce(3+)-mont.
- Tateiwa, Jun-ichi,Horiuchi, Hiroki,Uemura, Sakae
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p. 4039 - 4043
(2007/10/02)
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- Anodic Oxidation of Xylenes. Electrochemical Obtention of Cyclohexa-1,4-diene Derivatives
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cis- and trans-3,6-dimethoxy-3,6-dimethylcyclohexa-1,4-dienes obtained by methoxylation of p-xylene were completely separated.The unequivocal structure of the trans isomer was assigned by X-ray diffraction, and the cis:trans ratio is satisfactorily explained by an EECrCp mechanism.When the substrates were p- and o-xylene, the nuclear-addition products were obtained in a two-electron process, but when the substrate was m-xylene, the major muclear-addition product was obtained in a four-electron process.
- Barba, Isidoro,Alonso, Francisco,Florencio, Feliciana
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p. 4365 - 4367
(2007/10/02)
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