- Simple metal salts supported on montmorillonite as recyclable catalysts for intramolecular hydroalkoxylation of double bonds in conventional and VOC-exempt solvents
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We describe herein an efficient and particularly sustainable catalytic system for the intramolecular hydroalkoxylation of double bonds. A heterogeneous catalyst based on the impregnation of benign metals such as iron and bismuth on montmorillonite was used for a highly atom-economic transformation in DMC, a non-VOC solvent. The transformation allowed the formation of a large range of cyclic ethers from the corresponding unsaturated alcohols and the catalyst could be recycled several times.
- Notar Francesco, Irene,Cacciuttolo, Bastien,Pucheault, Mathieu,Antoniotti, Sylvain
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Read Online
- Design, synthesis, and testing of potential antisickling agents. 10. (2,2-Dimethylchroman-6-yl)alkanoic acids
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Five (2,2-dimethylchroman-6-yl)alkanoic acids were synthesized and tested for antigelling activities. It was envisioned that these agents might bind via hydrophobic bonding to nonpolar sites of the 'donor-acceptor' regions of hemoglobin S. Several (2,2-di
- Fatope,Abraham
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Read Online
- Annulation of phenols: Catalytic behavior of conventional and 2d zeolites
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Catalytic behavior of MFI zeolites differing in thickness of nanosheets and ordering was studied in annulation of phenols, and compared with 3D zeolites BEA and MFI containing large or medium pores as well as with micro/mesoporous zeolite USY. The highest
- Opanasenko, Maksym V.,Shamzhy, Mariya V.,Jo, Changbum,Ryoo, Ryong,Cejka, Jiri
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Read Online
- An improved method for synthesis of 1-benzopyrans from unsaturated alcohols and phenols using a catalytic amount of acids
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1-Benzopyrans, such as chromans and chromenes, were prepared in good to excellent yields by using a catalytic amount of p-toluenesulfonic acid through intermolecular cyclization reaction of phenols with unsaturated alcohols in 1,2-dichlroroethane.
- Ishino,Mihara,Hayakawa,Miyata,Kaneko,Miyata
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Read Online
- Facile synthesis of 2,2-Dimethylchromans by Mo(CO)6 Catalyzed reaction of aryl prenyl ethers
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2,2-Dimethylchromans 3a-g are synthesized in good yields by a one-pot reaction of the aryl prenyl ethers 1a-g with a catalytic amount of Mo(CO)6 in refluxing toluene.
- Bernard, Angela M.,Cocco, Maria T.,Onnis, Valentina,Piras, Pier P.
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Read Online
- Microwave-assisted aromatic C-O bond formation: A rapid and efficient method for the synthesis of aryl ethers
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A rapid and efficient aromatic C-O bond formation has been developed based on microwave-assistant, which is particularly useful for the intramolecular coupling of halides with alcohols. This method needs not the use of transition-metal catalyst. It was also demonstrated that the method can be used in the synthesis of bioactive natural flavans. Copyright
- Xu, Boyan,Xue, Jijun,Zhu, Jianrong,Li, Ying
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Read Online
- RAR-ALPHA COMPOUNDS FOR INFLAMMATORY DISEASE AND MALE CONTRACEPTION
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Modulators of retinoid acid receptor-alpha (RARα) of formula (I) are provided herein, as well as pharmaceutical compositions and methods relating thereto.
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Paragraph 0107-0108
(2021/06/26)
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- Axially Chiral 1,1'-Binaphthyl-2-Carboxylic Acid (BINA-Cox) as Ligands for Titanium-Catalyzed Asymmetric Hydroalkoxylation
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Axially chiral, enantiopure 1,1'-binaphthyl-2-carboxylic acids (BINA-Cox) have recently been introduced as chiral ligands for transition metal catalysis. Together with equimolar, co-catalytic amounts of Ti(OiPr)4 and water they form an in situ catalyst that performs the asymmetric catalytic hydroalkoxylation of 2-allylphenols to 2-methylcoumarans at high temperature (240 °C, microwave heating). The synthesis of reference ligand 2'-MeO-BINA-Cox (L1) has been optimized and performed at molar scale. Synthetic routes have been developed to access a variety of substituted BINA-Cox ligands (>30 examples), which have been tested for ligand effects on the reference asymmetric cyclization of 2-allylphenol. The substrate range of asymmetric catalytic hydroalkoxylation has been explored through systematic substrate structure variations to define scope and limitations of the titanium-catalyzed process. The new substrates 2-(1-vinylcycloalkyl)phenols (1j, 1k), 2-(2-vinylphenyl)propan-2-ol (1t), and 2'-vinyl-[1,1'-biphenyl]-2-ol (1u) are shown to undergo asymmetric catalytic cyclization to benzodihydrofurans and benzo[c]chromene, respectively.
- Blazejak, Max,Helmbrecht, Sebastian L.,Hintermann, Lukas,Schlüter, Johannes
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supporting information
(2020/04/15)
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- ZnI2/Zn(OTf)2-TsOH: A versatile combined-Acid system for catalytic intramolecular hydrofunctionalization and polyene cyclization
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A mild and efficient combined-Acid system using a zinc(ii) salt [ZnI2 or Zn(OTf)2] and p-Toluene sulfonic acid (TsOH) was investigated for catalytic cationic cyclizations, including intramolecular hydrocarboxylation, hydroalkoxylation, hydroamination, hydroamidation, hydroarylation and polyene cyclizations. This reaction provides easy access to five-and six-membered O-and N-containing saturated heterocyclic compounds, tetrahydronaphthalene derivatives and polycyclic skeletons in excellent yield with perfect Markovnikov selectivity and under mild conditions. The operational simplicity, broad applicability, and use of inexpensive commercially available catalysts make this protocol superior to existing methodologies.
- Chou, Ting-Hung,Yu, Bo-Hung,Chein, Rong-Jie
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supporting information
p. 13522 - 13525
(2019/11/14)
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- Alkylation of Phenol And Hydroquinone by Prenol in the Presence of Organoaluminum Catalysts
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Prenylphenols and 2,2-dimethylbenzopyrans were synthesized via alkylation of phenol and hydroquinone with prenol in the presence of organoaluminum catalysts, i.e., aluminum phenoxide and isopropoxide. Reaction products were isolated and characterized. Sev
- Chukicheva, I. Yu.,Fedorova,Koroleva,Kuchin
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- Simple salts of abundant metals (Fe, Bi, and Ti) supported on montmorillonite as efficient and recyclable catalysts for regioselective intramolecular and intermolecular hydroalkoxylation reactions of double bonds and tandem processes
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The transfer of catalytic hydroalkoxylation reactions of olefins from homogeneous to heterogeneous conditions has been studied using two types of solid catalysts, namely montmorillonite (MMT) doped with metal cations and metal nanoparticles supported on oxides. In the case of intramolecular reactions, 38-99% yields of cyclic ethers have been obtained using Fe-MMT and Bi-MMT both in CH3NO2 and dimethyl carbonate (DMC) compared with other supported metal salts or metal nanoparticles. In the case of more challenging intermolecular reactions, conversions up to 72% and yields up to 54% were obtained with metal-doped MMT as well, such as Fe-, Bi-, and Ti-MMT. In this paper, we detail the substrate scope and limitations for both classes of reactions and tandem processes, their transposition in flow and some mechanistic insights concerning the active species, in processes identified as truly heterogeneously catalysed. As a general trend, it was observed that trisubstituted double bonds allowed the best results both in intra- and intermolecular reactions. The transfer of homogeneous catalysts onto heterogeneous ones in the case of Fe-MMT and Bi-MMT was successful and even allowed enhanced catalytic activities in the case of Bi-MMT.
- Notar Francesco, Irene,Cacciuttolo, Bastien,Pascu, Oana,Aymonier, Cyril,Pucheault, Mathieu,Antoniotti, Sylvain
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p. 19807 - 19818
(2016/03/01)
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- Practical synthesis of a chromene analog for use as a retinoic acid receptor alpha antagonist lead compound
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Retinoic acid receptor alpha (RARα) selective compounds may guide the design of drugs that can be used in conjunction with hormonal adjuvant therapy in the treatment of breast cancer. Herein we report a modified synthesis of a known RARα antagonist, 2-fluoro-4-[[[8-bromo-2,2-dimethyl-4-(4- methylphenyl)chroman-6-yl]carbonyl]amino]benzoic acid and a synthesis of its unknown, desfluoro analog, 4-[[[8-bromo-2,2-dimethyl-4-(4-methylphenyl)chroman- 6-yl]carbonyl]amino]benzoic acid. The modified route allows for facile reaction workups, increased yields, lower cost and incorporates a green alternative step. Structure-activity relationship studies determined through functional cell-based assays, demonstrated antagonism to RARα for both compounds. Molecular modeling within the RARα binding pocket was used to compare binding interactions of the desfluoro analog to a known RAR antagonist.
- Jetson, Rachael,Malik, Neha,Luniwal, Amarjit,Chari, Venkatesh,Ratnam, Manohar,Erhardt, Paul
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supporting information
p. 104 - 108
(2013/07/27)
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- GPR120 RECEPTOR AGONISTS AND USES THEREOF
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GPR120 agonists are provided. These compounds are useful for the treatment of metabolic diseases, including Type II diabetes and diseases associated with poor glycemic control.
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Page/Page column 86
(2012/01/06)
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- GPR120 RECEPTOR AGONISTS AND USES THEREOF
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GPR120 agonists are provided. These compounds are useful for the treatment of metabolic diseases, including Type II diabetes and diseases associated with poor glycemic control.
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Page/Page column 26-27
(2012/01/13)
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- Selective sp3 C-H bond activation based on a carbocation relay: Friedel-Crafts reaction with alkanes as the alkylating component
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A highly efficient and selective intramolecular Friedel-Crafts reaction of 3-methylbutyl or 4-methylpentyl-substituted aromatics has been developed using a carbocation relay strategy through selective sp3 C-H bond activation, providing a facile and cost-effective approach for the construction of benzocyclic compounds. A variety of 1,1-dimethylindane and naphthalene derivatives have been prepared from very simple starting materials in good yields with high selectivity. The present strategy has provided a new example of a Friedel-Crafts reaction with alkanes as the alkylating component and constitutes a convenient approach to selective C-H bond activation and functionalization of alkane derivatives. A highly efficient and selective intramolecular Friedel-Crafts reaction of 3-methylbutyl or 4-methylpentyl- substituted aromatics has been developed using a carbocation relay strategy through selective sp3 C-H bond activation. The approach provides a facile and cost-effective route to benzocyclic compounds. Copyright
- Wang, Jie,Zhou, Pengfei,Wang, Yang
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experimental part
p. 264 - 270
(2011/03/20)
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- Hidden Bronsted acid catalysis: Pathways of accidental or deliberate generation of triflic acid from metal triflates
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The generation of a hidden Bronsted acid as a true catalytic species in hydroalkoxylation reactions from metal precatalysts has been clarified in case studies. The mechanism of triflic acid (CF3SO3H or HOTf) generation starting either from AgOTf in 1,2-dichloroethane (DCE) or from a Cp*RuCl2/AgOTf/phosphane combination in toluene has been elucidated. The deliberate and controlled generation of HOTf from AgOTf and cocatalytic amounts of tert-butyl chloride in the cold or from AgOTf in DCE at elevated temperatures results in a hidden Bronsted acid catalyst useful for mechanistic control experiments or for synthetic applications.
- Dang, Tuan Thanh,Boeck, Florian,Hintermann, Lukas
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experimental part
p. 9353 - 9361
(2012/01/04)
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- An efficient preparation of chroman derivatives from 3-aryl-1-propanols and related compounds with 1,3-diiodo-5,5-dimethylhydantoin under irradiation conditions
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Treatment of various 3-aryl-1-propanols with 1,3-diiodo-5,5- dimethylhydantoin (DIH) in ethyl acetate or 1,2-dichloroethane under irradiation with a tungsten lamp gave the corresponding chroman derivatives in good to moderate yields. The present reaction proceeds via the initial formation of an alkoxyl radical and the radical cyclization onto the aromatic ring, followed by the oxidation of the formed radical intermediate with DIH to provide the chroman derivative. The same treatment of o-biphenyldimethylcarbinol, o-phenylbenzoic acid, and o-alkylbenzoic acids with DIH provided the corresponding chroman derivatives and lactone derivatives in good yields, respectively. Georg Thieme Verlag Stuttgart - New York.
- Furuyama, Shusuke,Togo, Hideo
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scheme or table
p. 2325 - 2329
(2010/11/16)
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- GPR120 RECEPTOR AGONISTS AND USES THEREOF
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GPR120 agonists are provided. These compounds are useful for the treatment of metabolic diseases, including Type II diabetes and diseases associated with poor glycemic control.
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Page/Page column 61-62
(2010/08/04)
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- InIII-catalysed tandem C-C and C-O bond formation between phenols and allylic acetates
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Indium triflate catalysed tandem allylation-intramolecular hydroalkoxylation was efficiently carried out by using 1 mol-% of the catalyst under mild conditions to afford the dihydrobenzopyran ring system (chroman-type structure) in good yields. Kinetic, mechanistic and theoretical studies are also presented. Tandem allylation-intramolecular hydroalkoxylation carried out in the presence of an indium catalyst (1 mol-%) under mild conditions provides the dihydrobenzopyranring system in good yields. Kinetic, mechanistic and theoretical studies are presented.
- Vece, Vito,Ricci, Jeremy,Poulain-Martini, Sophie,Nava, Paola,Carissan, Yannick,Humbel, Stephane,Dunach, Elisabet
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supporting information; experimental part
p. 6239 - 6248
(2010/12/29)
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- A recyclable copper(II) catalyst for the annulation of phenols with 1,3-dienes
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Air- and moisture-stable Cu(OTf)2-bipy catalyses the addition of phenols to 1,3-dienes under aerobic conditions in a tandem hydroalkoxylation- rearrangement-hydroalkylation sequence, furnishing O-heterocycles in moderate to good yields, and can be recycled without any loss in catalytic activity. The Royal Society of Chemistry.
- Adrio, Luis A.,Hii, King Kuok
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supporting information; scheme or table
p. 2325 - 2327
(2009/02/03)
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- Novel synthesis of naturally occurring pulvinones: A heck coupling, transesterification, and Dieckmann condensation strategy
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Phosphine-free Heck alkenylations of iodoarenes with trifluoroethyl 2-acetoxyacrylate (19) led stereoselectively to trifluoroethyl (Z)-2-acetoxycinnamates 31-34, 42, 44, and 51. Deacetylation followed by acylation with N,N′-dicyclohexylcarbodiimide activa
- Bernier, David,Brueckner, Reinhard
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p. 2249 - 2272
(2008/03/12)
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- Synthesis of 1,1-dimethyl-4-indanol derivatives
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The synthesis of 1,1-dimethyl-4-indanols (3a,b) has been achieved by intramolecular Friedel-Crafts cyclization of 2-(3-methyl-2-butenyl)phenols (5a,b) or 1-methoxy-2-(3-methyl-2-butenyl)benzenes (6a,b) followed by demethylation, respectively. It was found that the solvent was critical for the formation of different products in the intramolecular Friedel-Crafts reactions of 6. The unexpected product 4-methoxy-1,1,6,6-tetramethyl-as-hydrindacene (11) was obtained from the Friedel-Crafts reactions of 6a and its structure was confirmed by X-ray diffraction analysis. The key intermediates 5a,b were prepared by ortho-alkenylation of phenols with 1-bromo-3-methyl-2-butene, and the reaction temperature exerted an obvious impact on the yield of 2-(3-methyl-2-butenyl)phenol (5a). Copyright Taylor & Francis Group, LLC.
- Wang, Yang,Wu, Jiang,Xia, Peng
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p. 2685 - 2698
(2007/10/03)
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- Ag(I)-catalyzed sequential C-C and C-O bond formations between phenols and dienes with atom economy
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Mild, efficient, and economical Ag(I)-catalyzed sequential C-C/C-O bond formations between phenols and dienes were developed to afford in good yields a variety of dihydrobenzopyran and dihydrobenzofuran ring systems, which are important motifs in both naturally occurring and biologically active compounds.
- Youn, So Won,Eom, Jeong Im
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p. 6705 - 6707
(2007/10/03)
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- Investigation of the Montmorillonite clay-catalyzed [1,3] shift reaction of 3-methyl-2-butenyl phenyl ether
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The [1,3] shift reaction of 3-methyl-2-butenyl phenyl ether was catalyzed more effectively by Montmorillonite K10 clay than Montmorillonite KSF clay, and proceeded with greatest ortho-selectivity in carbon tetrachloride at room temperature.
- Dintzner, Matthew R.,Morse, Kara M.,McClelland, Kristen M.,Coligado, Deborah M.
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- Montmorillonite clays in organic synthesis: A one-pot conversion of phenols to 2,2-dimethylbenzopyrans
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2,2-Dimethylbenzopyran derivatives were generated through a one-pot Montmorillonite K10 clay-catalyzed condensation of substituted phenols with prenyl bromide.
- Dintzner, Matthew R.,McClelland, Kristen M.,Morse, Kara M.,Akroush, Michael H.
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p. 2028 - 2030
(2007/10/03)
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- Catalyst for aromatic C—O, C—N, and C—C bond formation
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The present invention is directed to a transition metal catalyst, comprising a Group 8 metal and a ligand having the structure wherein R, R′ and R″ are organic groups having 1-15 carbon atoms, n=1-5, and m=0-4. The present invention is also directed to a method of forming a compound having an aromatic or vinylic carbon-oxygen, carbon-nitrogen, or carbon-carbon bond using the above catalyst. The catalyst and the method of using the catalyst are advantageous in preparation of compounds under mild conditions of approximately room temperature and pressure.
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- Air stable, sterically hindered ferrocenyl dialkylphosphines for palladium-catalyzed C-C, C-N, and C-O bond-forming cross-couplings
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Pentaphenylferrocenyl di-tert-butylphosphine has been prepared in high yield from a two-step synthetic procedure, and the scope of various cross-coupling processes catalyzed by complexes bearing this ligand has been investigated. This ligand creates a remarkably general palladium catalyst for aryl halide amination and for Suzuki coupling. Turnovers of roughly 1000 were observed for aminations with unactivated aryl bromides or chlorides. In addition, complexes of this ligand catalyzed the formation of selected aryl ethers under mild conditions. The reactions encompassed electron-rich and electron-poor aryl bromides and chlorides. In the presence of catalysts containing this ligand, these aryl halides coupled with acyclic or cyclic secondary alkyl- and arylamines, with primary alkyl- and arylamines, and with aryl- and primary alkylboronic acids. These last couplings provide the first general procedure for reaction of terminal alkylboronic acids with aryl halides without toxic or expensive bases. The ligand not only generates highly active palladium catalysts, but it is air stable in solution and in the solid state. Palladium(0) complexes of this ligand are also air stable as a solid and react only slowly with oxygen in solution.
- Kataoka, Noriyasu,Shelby, Quinetta,Stambuli, James P.,Hartwig, John F.
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p. 5553 - 5566
(2007/10/03)
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- Some Phenoxy-2H-benzo[b]pyrans
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Successful methods have been developed for the syntheses of 6-, 7- and 8-phenoxy-2H-benzo-[b]pyrans, 4-,5-,6-,7- and 8-phenoxy-2,2-dimethyl-2H-benzo[b]pyrans and 4- and 7-phenoxy-2,2-diphenyl-2H-benzo[b]pyrans.
- Firth, John W.,Livingstone, Robert
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p. 801 - 820
(2007/10/03)
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- Molybdenum(II)-catalyzed allylation of electron-rich aromatics and heteroaromatics
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The stable, readily available molybdenum(II) complexes [Mo(CO)4Br2]2 (B) and Mo(CO)3(MeCN)2-(SnCl3)Cl (C) have been found to catalyze C-C bond- forming allylic substitution with electronrich aromatics (e.g., 15 + PhOMe → 62) and heteroaromatics (e.g., 15 + 36 → 88) as nucleophiles under mild conditions (room temperature, 30 min-3 h). Remarkable is the para-selectivity for anisole, whereas phenol tends to favor ortho-substitution in certain instances. Mechanistic and stereochemical experiments are indicative of Lewis-acid catalysis rather than a metal template-controlled process.
- Malkov, Andrei V.,Davis, Stuart L.,Baxendale, Ian R.,Mitchell, William L.,Kocovsky, Pavel
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p. 2751 - 2764
(2007/10/03)
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- Synthesis and use of retinoid compounds having negative hormone and/or antagonist activities
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Aryl-substituted and aryl and (3-oxo-1-propenly)-substituted benzopyran, benzothiopyran, 1,2-dihydroquinoline, and 5,6-dihydronaphthalene derivatives have retinoid negative hormone and/or antagonist-like biological activities. The invented RAR antagonists can be administered to mammals, including humans, for the purpose of preventing or diminishing action of RAR agonists on the bound receptor sites. Specifically, the RAR agonists are administered or coadministered with retinoid drugs to prevent or ameliorate toxicity or side effects caused by retinoids or vitamin A or vitamin A precursors. The retinoid negative hormones can be used to potentiate the activities of other retinoids and nuclear receptor agonists. For example, the retinoid negative hormone called AGN 193109 effectively increased the effectiveness of other retinoids and steroid hormones in in vitro transactivation assays. Additionally, transactivation assays can be used to identify compounds having negative hormone activity. These assays are based on the ability of negative hormones to down-regulate the activity of chimeric retinoid receptors engineered to possess a constitutive transcription activator domain.
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- The reactivity of o-hydroxybenzyl alcohol and derivatives in solution at elevated temperatures
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The reactivity of o-hydroxybenzyl alcohol (o-HBA, 1), as a model compound for lignin, has been studied in various solvents between 390 and 560 K. Both in polar and apolar solvents the benzylic cation is the reactive intermediate. In alcoholic solvents, the benzylic cation reacts with the solvent to give the corresponding ethers. Relative reaction rates have been determined for different alcohols; a factor of 14 is encountered between the most (methanol) and least (tert-butyl alcohol) reactive ones. The etherification is reversible, in contrast to the electrophilic aromatic substitution with phenol and anisole, for which k(PhOH) = 1 X 105 M-1 s- 1 and k(anisole) = 1 x 104 M-1 s-1, at 424 K. In apolar hydroaromatic solvents, 7H-benz[de]anthracene, 9,10-dihydroanthracene, and 9,10- dihydrophenanthrene, the formation of o-cresol proceeds via hydride transfer from the solvent to the benzylic cation; rate constants at 555 K are 2 x 106, 5 x 104, and 5 x 103 M-1 s-1, respectively.
- Dorrestijn, Edwin,Kranenburg, Marieke,Ciriano, Maria Victoria,Mulder, Peter
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p. 3012 - 3018
(2007/10/03)
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- Reaction between phenols and isoprene under zeolite catalysis. Highly selective synthesis of chromans and o-isopentenylphenols
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Chromans 3 and o-isopentenylphenols 4 are synthesized in satisfactory to good yields and selectivities by the reaction of phenols and isoprene in the presence of the commercially available acid faujasite zeolite HSZ-360.
- Bigi, Franca,Carloni, Silvia,Maggi, Raimondo,Muchetti, Chiara,Rastelli, Massimo,Sartori, Giovanni
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p. 301 - 304
(2007/10/03)
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- Identification of highly potent retinoic acid receptor α-selective antagonists
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The syntheses and full retinoid receptor characterization of a novel series of retinoic acid receptor α (RARα) antagonists, 1-5, are described. These compounds bind with high affinity to RARα but were completely inactive in gene transactivation. They were also potent and effective antagonists of retinoic acid (RA) induced gene transcription at RARα. Compounds 1-5 exhibited varying degrees of selectivity for RARα relative to RARβ/γ, with compound 5 being the most selective in both binding and functional antagonism assays. These compounds will be invaluable tools in delineating the physiological roles of RARα in development and in the adult animal and may themselves be useful therapeutic agents in human diseases associated with RARα.
- Teng, Min,Duong, Tien T.,Johnson, Alan T.,Klein, Elliott S.,Wang, Liming,Khalifa, Berket,Chandraratna, Roshantha A. S.
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p. 2445 - 2451
(2007/10/03)
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- Chromenes and chromanones. Part IV.1 The Birch reduction of 2,2-dimethyl-4-chromanone and its 7-substituted analogues
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2,2-Dimethyl-4-chromanone (1a), 2,2,7-trimethyl-4-chromanone (1b) and 7-methoxy-2,2-dimethyl-4-chromanone (1c) have been reduced by sodium or lithium in liquid ammonia with the presence or without of proton donor. The bicyclic or phenolic products were obtained. Products with reduced benzene ring only were also observed. The possible mechanisms of reductions are considered.
- Aniol, Miroslaw
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p. 1069 - 1079
(2007/10/03)
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- CHROMENES AND CHROMANONES. PART 1 THE BIRCH REDUCTION OF COUMARINS AND 2H-CHROMENES
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The reduction of coumarin, 4-methylcoumarin, 2,2-dimethyl-2H-chromene and 2,2,4-trimethyl-2H-chromene with sodium or lithium in liquid ammonia with the presence or without donor of protons was carried out.The formation of phenolic products was observed wh
- Aniol, Miroslaw,Lusiak, Przemyslaw,Wawrzenczyk, Czeslaw
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p. 991 - 1000
(2007/10/02)
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- REGIOSELECTIVE PRENYLATION OF PHENOLS BY PALLADIUM CATALYST: SYNTHESES OF PRENYLPHENOLS AND CHROMANS
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The palladium-catalyzed coupling reaction of iodophenols (1) with 2-methyl-3-butyn-2-ol gave alkynylphenols (2).Catalytic hydrogenation of 2 over Raney nickel and the subsequent dehydration of the resultant alkylphenols (3) gave regioselectively the desired prenylphenols (4).Dehydration of alkylphenols (3f-h) gave chromans (7).
- Tsukayama, Masao,Kikuchi, Makoto,Kawamura, Yasuhiko
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p. 1487 - 1490
(2007/10/02)
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- Chroman esters of phenols and benzoic acids having retinoid-like activity
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Retinoid like activity is exhibited by compounds of the formula STR1 wherein the R 1 -R 7 groups are independently H or straight chain or branched chain lower alkyl or cycloalkyl of 1 to 6 carbons; X symbolizes an ester or thioester linkage, Y is cycloalk
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- -SIGMATROPIC REARRANGEMENTS OF THE ACETOACETATES OF ALLYL ALCOHOLS (CARROLL REACTION) AND ALLYLPHENYL ETHERS (CLAISEN REACTION) ON THE SURFACE OF ADSORBENTS
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A method has been developed for effecting rearrangements of allylacetoacetates to γ,δ-unsaturated ketones (Carroll rearrangement) and allylaryl ethers to the corresponding allylphenols (Claisen rearrangement) under conditions of adsorption on aluminum oxide and silica gel.The method provides a sharp reduction of the temperature of these reactions and improvement of their efficiency.
- Pogrebnoi, S. I.,Kal'yan, Yu. B.,Krimer, M. Z.,Smit, V. A.
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p. 733 - 739
(2007/10/02)
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- Clay catalyzed rearrangement of substituted allyl phenyl ethers: Synthesis of ortho-allyl phenols, chromans and coumarans
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Montmorillonite clays catalyze the rearrangement of substituted allyl phenyl ethers to provide ortho-allyl phenols, chromans and coumarans under mild conditions.
- Dauben, William G.,Cogen, Jeffrey M.,Behar, Victor
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p. 3241 - 3244
(2007/10/02)
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- Synthetic and Stereochemical Studies of the Octahydro-1-benzopyran System
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The cis and trans isomers of the octahydro-1-benzopyran system have been synthesised and their conformations studied by low-temperature (13)C and highfield (1)H n.m.r. spectroscopy.The position of the conformational equilibrium in the cis isomer at -70 deg C in CDCl3-CFCl3 (50:50) has been determined as approximately 99.5:0.5 (ΔG0 -8.9 kJ mol-1) in favour of the conformation having the oxygen axially disposed towards the cyclohexane ring.
- Griffiths, D. Vaughan,Wilcox, Geoffrey
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p. 431 - 436
(2007/10/02)
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- A new regioselective synthesis of 2,3,4,5-tetrahydro-6H-oxepino[3,2-c]pyran-6-ones, and [1]benzopyran-6-ones
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Through an anti-Markovnikow hydration of some olefin derivatives of 4-hydroxy-2-pyrones, and 4-hydroxy-coumarins, followed by a regioselective intramolecular dehydration, involving the primary alcohols obtained and the enolic oxygen of the rings, promoted by Amberlyst 15 in boiling toluene, the new heterocycles 2,3,4,5-tetrahydro-6H-oxepino[3,2-c]pyran-6-one and [1]benzopyran-6-ones, were obtained in fair yields.
- Bravo,Frigerio,Ticozzi
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p. 647 - 649
(2007/10/02)
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- Ortho-Selective Alkylation of Phenols with Symmetric Sulfides and Sulfuryl Chloride
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Sulfuryl chloride has been shown to be useful activator for sulfides in the selective preparation of ortho-alkylated phenols via sigmatropic rearrangement.By this process, ortho-alkylated phenols have been prepared with various symmetric sulfides in good yields.The rearrangement products having 3-chloropropyl or 3-methyl-3-butenyl moiety have been converted into 2H-1-benzopyran derivatives.
- Sato, Kikumasa,Inoue, Seiichi,Miyamoto, Osamu,Ikeda, Hiroshi,Ota, Tomomi
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p. 4184 - 4186
(2007/10/02)
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- Organic Synthesis with sulfones. XLI. Nucleophilic substitution of allylic sulfones
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The sulfonyl group in allylic sulfones can be displaced by a variety of nucleophiles.The reaction is particularly easy with tertiary sulfones, i.e. bearing no hydrogen atoms at the α-position.Lewis acids catalyse the displacement reaction.
- Julia, Marc,Nel, Maurice,Uguen, Daniel
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p. 487 - 492
(2007/10/02)
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- REGIOSPECIFIC ALKENYLATION OF PHENOLS BY ISOPRENE PROMOTED BY Pt(II) AND Pd(II) COMPLEXES
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Catalytic alkenylation of phenols with isoprene is promoted by Pd(II) or Pt(II) complexes.Ortho-isopentenylphenols are obtained together with the corresponding 2,2-dimethylchromans.The catalytic activity of the two d8 ions is compared.A possible mechanism is discussed.
- Felice, Vincenzo De,Renzi, Augusto De,Funicello, Maria,Panunzi, Achille,Saporito, Antonio
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- REGIOSPECIFIC ALKENYLATION OF PHENOLS BY 1,1-DIMETHYLALLENE PROMOTED BY PLATINUM CATALYSTS
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1,1-Dimethylallene reacts with phenolic substrates in the presence of catalytic amounts of platinum(II) complexes.A regiospecific C-alkenylation takes place, affording o-isopentenylphenols and 2,2-dimethylchromans.Possible reaction mechanisms are also discussed.
- Renzi, Augusto De,Panunzi, Achille,Saporito, Antonio,Vitagliano, Aldo
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p. 993 - 996
(2007/10/02)
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