- Investigating the microwave-accelerated Claisen rearrangement of allyl aryl ethers: Scope of the catalysts, solvents, temperatures, and substrates
-
The microwave-accelerated Claisen rearrangement of allyl aryl ethers was investigated, in order to gain insight into the scope of the catalysts, solvents, temperatures, and substrates. Among the catalysts examined, phosphomolybdic acid (PMA) was found to greatly accelerate the reaction in NMP, at temperatures ranging from 220 to 300 °C. This method was found to be useful for preparing several intermediates previously reported in the literature using precious metal catalysts such as Au(I), Ag(I), and Pt(II). Additionally, substrates bearing bromo and nitro groups on the aryl portion required careful tailoring of the reaction conditions to avoid complex product profiles.
- Hui, Zi,Jiang, Songwei,Qi, Xiang,Ye, Xiang-Yang,Xie, Tian
-
supporting information
(2020/05/18)
-
- Green Organocatalytic Synthesis of Dihydrobenzofurans by Oxidation-Cyclization of Allylphenols
-
A green and cheap protocol for the synthesis of dihydrobenzofurans via an organocatalytic oxidation of o -allylphenols is presented. The use of 2,2,2-trifluoroacetophenone and H 2 O 2 as the oxidation system, leads to a highly useful synthetic method, where a variety of substituted o -allylphenols were cyclized in high yields..
- Triandafillidi, Ierasia,Sideri, Ioanna K.,Tzaras, Dimitrios Ioannis,Spiliopoulou, Nikoleta,Kokotos, Christoforos G.
-
supporting information
p. 4254 - 4260
(2017/09/12)
-
- Regioselective Alkoxycarbonylation of Allyl Phenyl Ethers Catalyzed by Pd/dppb under Syngas Conditions
-
A simple and regioselective synthesis of phenoxy esters and phenylthio esters is reported. The products are obtained by selective alkoxycarbonylation catalyzed by Pd2(dba)3, 1,4-bis(diphenylphisphino)butane (dppb), and syngas (CO/H2) in chloroform/alcohol. This methodology affords bifunctional products in good yield with excellent n-selectivity and without the need to use additives.
- Amézquita-Valencia, Manuel,Alper, Howard
-
p. 3860 - 3867
(2016/05/24)
-
- PdI2-catalyzed regioselective cyclocarbonylation of 2-allyl phenols to dihydrocoumarins
-
A simple, efficient, and regioselective synthesis of 3-methyl-3,4-dihydrocoumarins is reported. The reaction of 2-allyl phenols with synthesis gas was catalyzed by PdI2, and 1,3,5,7-tetramethyl-6-phenyl-2,4,8-trioxa-6-phosphaadamantane (L1) and 1,3,5,7-tetramethyl-6-tetradecyl-2,4,8-trioxa-6-phosphaadamantane (L2) were effective as ligands, affording good product selectivity in all cases.
- Amzquita-Valencia, Manuel,Alper, Howard
-
supporting information
p. 5827 - 5829
(2015/01/08)
-
- An efficient palladium-catalyzed synthesis of cinnamyl ethers from aromatic halides, phenols, and allylic chloride
-
A one-pot, two-step catalytic protocol for the preparation of cinnamyl ethers from simple and readily available aryl halides, phenols and allyl chloride is reported for the first time. This simple and highly efficient palladium nanoparticles catalytic system shows good regio- and stereoselectivities and affords the desired products in good to high yields (49-85%) from aryl iodides. Furthermore, less reactive aryl bromides can also give the cinnamyl ethers in moderate yields (24-72%).
- Wang, Wei,Zhou, Rong,Jiang, Zhi-Jie,Wang, Kun,Fu, Hai-Yan,Zheng, Xue-Li,Chen, Hua,Li, Rui-Xiang
-
supporting information
p. 616 - 622
(2014/05/20)
-
- Copper(I)-catalyzed aryl bromides to form intermolecular and intramolecular carbon-oxygen bonds
-
(Chemical Equation Presented) A highly efficient Cu-catalyzed C-O bond-forming reaction of alcohol and aryl bromides has been developed. This transformation was realized through the use of copper(I) iodide as a catalyst, 8-hydroxyquinoline as a ligand, and K3PO4 as a base. A variety of functionalized substrates were found to react under these reaction conditions to provide products in good to excellent yields.
- Niu, Jiajia,Guo, Pengran,Kang, Juntao,Li, Zhigang,Xu, Jingwei,Hu, Shaojing
-
supporting information; experimental part
p. 5075 - 5078
(2009/10/17)
-
- An efficient Ullmann-type C-O bond formation catalyzed by an air-stable copper(I)-bipyridyl complex
-
(Chemical Equation Presented) An efficient O-arylation of phenols and aliphatic alcohols with aryl halides was developed that uses an air-stable copper(I) complex as the catalyst. This arylation reaction can be performed in good yield in the absence of Cs2CO3. A variety of functional groups are compatible with these reaction conditions with low catalyst loading levels.
- Niu, Jiajia,Zhou, Hua,Li, Zhigang,Xu, Jingwei,Hu, Shaojing
-
p. 7814 - 7817
(2008/12/22)
-
- Process for the preparation of lactones and aromatic hydroxycarboxylic acids
-
Verfahren zur Herstellung von gegebenenfalls substituierten Hydroxyphenylessigs?uren der Formel in der n 0, 1 2 oder 3 sein kann, R H oder einen C1-C6-Alkylrest, C1-C6-Alkoxyrest, Phenyl, Phenoxy, CN, NO2, SO3H, NH2, F, Cl, I oder Br oder einen 5- oder 6-gliedrigen Ring mit einem N-Atom, der an den Phenylring anelliert ist bedeutet und die Reste X und Y OH, H, ein C1-C6-Alkylrest, ein C1-C6-Alkoxyrest, Phenyl, Phenoxy, CN, NO2, SO3H, NH2, F, Cl, I oder Br sein k?nnen, wobei mindestens einer der Reste X oder Y OH bedeutet oder von gegebenenfalls substituierten Lactonen der Formel bei welchem ein Allylphenol der Formel in Wasser, einem C1-C6-Alkohol oder einem Wasser/Alkoholgemisch mit Ozon korrespondierenden Aldehyd umgesetzt wird, der durch Erw?rmen mit den bei der Ozonolyse entstehenden Peroxiden zur entsprechenden Hydroxyphenylessigs?ure der Formel (I) aufoxidiert wird, die gegebenenfalls, für den Fall, dass X gleich OH ist, zum Lacton der Formel (II) cyclisiert werden kann.
- -
-
-
- Preparation of aryl allyl ether in the recyclable ionic liquid [bmim]PF6
-
The recyclable room temperature ionic liquid [bmim]PF6, namely 1-butyl-3-methyl-imidazolium hexafluorophosphate, is used as an alternative solvent to dipolar aprotic solvents for the synthesis of aryl allyl ether by the Williamson method.
- Zhou, Mei-Yun,Li, Yi-Qun
-
p. 328 - 328
(2007/10/03)
-
- Zinc-catalyzed Williamson ether synthesis in the absence of base
-
A zinc-catalyzed Williamson ether synthesis is described with microwave heating in the presence of DMF or stirring in an oil-bath using THF as solvent and in the absence of base. Zinc powder was found to be a highly efficient catalyst for the synthesis of aromatic ethers using microwave heating in the presence of N,N-dimethylformamide as well as under stirring in an oil-bath using tetrahydrofuran as solvent without any inorganic base. This method can be used for selective mono-, di- or tri-O-alkylations.
- Paul, Satya,Gupta, Monika
-
p. 8825 - 8829
(2007/10/03)
-
- Enantiospecific synthesis of B-seco-C-aromatic taxanes
-
A simple and efficient methodology for the enantiospecific synthesis of B-seco-C-aromatic taxanes starting from monoterpene (R)-carvone is described. Coupling of 6,6-dimethylcarvone 5 with appropriate arylethyl bromides followed by oxidation generates the enones 7, 15, 25, which are transformed into the 20-nor-B-seco-C-aromatic taxane derivatives 11, 17 and B-seco-C-aromatic taxane derivative 29 via degradation of the isopropenyl group.
- Srikrishna,Reddy,Kumar,Gharpure
-
p. 905 - 914
(2007/10/03)
-
- Thermodynamic, spectroscopic, and density functional theory studies of allyl aryl and prop-1-enyl aryl ethers. Part 1. Thermodynamic data of isomerization
-
A chemical equilibration study of the relative thermodynamic stabilities of seventy isomeric allyl aryl ethers (a) and (Z)-prop-1-enyl aryl ethers (b) in DMSO solution has been carried out. From the variation of the equilibrium constant with temperature the Gibbs energies, enthalpies, and entropies of isomerization at 298.15 K have been evaluated. Because of their low enthalpies, the (Z)-prop-1-enyl aryl ethers are strongly favored at equilibrium, the Gibbs energies of the a→b isomerization ranging from -12 to -23 kJ mol-1. The entropy contribution is negligible in most reactions, but occasionally small positive values less than +10 J K-1 mol-1 of the entropy of isomerization are found. The equilibration studies were also extended to involve two pairs of related isomeric ethers with a Me substituent on C(2) of the olefinic bond. The Me substituent was found to increase the relative thermodynamic stability of the allylic ethers by ca. 3.4 kJ mol-1.
- Taskinen, Esko
-
p. 1824 - 1834
(2007/10/03)
-
- Intramolecular reactivity of functionalized arylcarbenes: 2-Allyloxyphenylcarbenes
-
2-Allyloxyphenylcarbenes (8) undergo intramolecular addition (→ 9) and (formal) C-H insertion (→ 11) competitively. Stereochemical labels indicate that 11 and major amounts of 9 arise from triplet 8. The intermolecular O-H insertion of singlet 8 with meth
- Gotzhein, Frank,Kirmse, Wolfgang
-
p. 1373 - 1376
(2007/10/03)
-
- Asymmetric dihydroxylation of aryl allyl ethers
-
Asymmetric dihydroxylation of substituted aryl allyl ethers is described. Para-substituents are shown to favor high enantioselectivity (89-95%ee), while ortho-groups have a deleterious effect (28-63%ee). Four medicinal agents were prepared: guaifenesin (expectorant), mephenesin (muscle relaxant), chlorphenesin (antifungal) and propanolol (β-blocker).
- Wang,Zhang,Sharpless
-
p. 2267 - 2270
(2007/10/02)
-
- A new and facile synthesis of chroman-3-ols, 3,4-dihydro-2H-[1]-benzopyran-3-ols
-
o-Allyl phenols react with m-chloroperoxybenzoic acid (m-CPBA) in dry chloroform to give chroman-3-ols in a single step in good yields (93-96%).
- Satyanarayana,Prasad Rao Ch.,Krupadanam,Srimannarayana
-
p. 1455 - 1464
(2007/10/02)
-
- Anodic Oxidation of (Trimethylsilyl)methanes with ?-Electron Substituents in the Presence of Nucleophiles
-
It was found that oxidation potentials of methanes with ?-electron substituents were decreased by introduction of a trimethylsilyl group.The anodic oxidation of benzyl-, allyl-, aryl(or alkyl)thiomethyl-, and aryloxymethyl-substituted trimethylsilanes smoothly proceeded in the presence of nucleophiles, e.g. alcohols and carboxylic acids, to eliminate the trimethylsilyl groups giving the corresponding alkoxylated and carboxylated products in moderate or high yields without full optimization of electrolytic conditions, while aminomethylsilanes did not undergo such a kind of anodic oxidation.
- Koizumi, Toshio,Fuchigami, Toshio,Nonaka, Tsutomu
-
p. 219 - 225
(2007/10/02)
-
- 929. Chrom-3-en-6-ols. The action of pyridine on alk-2-enyl-benzoquinones
-
Allylbenzoquinones are converted by treatment with pyridine into quinols and chrom-3-en-6-ols. The tendency for the latter reaction to occur increases as the benzoquinone ring becomes more highly substituted.
- McHale,Green
-
p. 5060 - 5064
(2007/10/08)
-