- Radical Cation Diels-Alder Reactions by TiO2 Photocatalysis
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Radical cation Diels-Alder reactions by titanium dioxide (TiO2) photocatalysis in lithium perchlorate/nitromethane solution are described. TiO2 photocatalysis promotes reactions between electron-rich dienes and dienophiles, which would otherwise be difficult to accomplish due to electronic mismatching. The reactions are triggered by hole oxidation of the dienophile and are completed by the excited electron reduction of the radical cation intermediate at the dispersed surface in the absence of any sacrificial substrate.
- Nakayama, Kaii,Maeta, Naoya,Horiguchi, Genki,Kamiya, Hidehiro,Okada, Yohei
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supporting information
p. 2246 - 2250
(2019/04/10)
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- Multienzyme One-Pot Cascade for the Stereoselective Hydroxyethyl Functionalization of Substituted Phenols
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The operability and substrate scope of a redesigned vinylphenol hydratase as a single biocatalyst or as part of multienzyme cascades using either substituted coumaric acids or phenols as stable, cheap, and readily available substrates are reported.
- Payer, Stefan E.,Pollak, Hannah,Schmidbauer, Benjamin,Hamm, Florian,Juri?i?, Filip,Faber, Kurt,Glueck, Silvia M.
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supporting information
p. 5139 - 5143
(2018/09/13)
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- Enantioselective Oxy-Heck–Matsuda Arylations: Expeditious Synthesis of Dihydrobenzofuran Systems and Total Synthesis of the Neolignan (?)-Conocarpan
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This work discloses the first examples of an effective enantioselective oxy-Heck–Matsuda reaction using a variety of styrenic olefins to generate chiral dihydrobenzofurans. The reaction proceeds in moderate to good yields, with high trans diastereoselectivity (up to 20:1) in enantioselectivities up to 90:10 using the N,N-ligand pyrimidine-bisoxazoline (PyriBox). The oxy-Heck–Matsuda reactions were carried out under mild conditions and rather low catalyst loadings. The feasibility and practicality of the process is demonstrated by a concise total synthesis of the neolignan (?)-conocarpan. X-ray diffraction of an advanced brominated intermediate in the route to (?)-conocarpan has allowed the unequivocal assignment of the absolute stereochemistry of the oxy-Heck–Matsuda aryldihydrobenzofuran products. A rationale for the mechanism operating in these enantioselective oxy-Heck–Matsuda reactions is also presented. (Figure presented.).
- Silva, Allan R.,Polo, Ellen C.,Martins, Nelson C.,Correia, Carlos Roque D.
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p. 346 - 365
(2018/01/26)
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- Pd-Boron-Catalyzed One Carbon Isomerization of Olefins: Water Assisted Process at Room Temperature
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A palladium-boronate/borane-system -catalyzed isomerization of olefins has been uncovered. An efficient catalytic combination of [Pd(OAc)2]3-boronate-PCy3-enabled olefin isomerization at 80 °C has been investigated. Addition of water to the reaction showed a remarkable improvement and the isomerization occurred at ambient temperature. These catalytic systems function efficiently for the isomerization of functionalized as well as unfunctionalized olefins. The catalytic conditions demonstrate the involvement of both nonhydride and metal-hydride medium and can be switchable with water as an additive.
- Ojha, Devi Prasan,Gadde, Karthik,Prabhu, Kandikere Ramaiah
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p. 4859 - 4865
(2017/05/12)
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- Allyl/propenyl phenol synthases from the creosote bush and engineering production of specialty/commodity chemicals, eugenol/isoeugenol, in Escherichia coli
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The creosote bush (Larrea tridentata) harbors members of the monolignol acyltransferase, allylphenol synthase, and propenylphenol synthase gene families, whose products together are able to catalyze distinct regiospecific conversions of various monolignols into their corresponding allyl- and propenyl-phenols, respectively. In this study, co-expression of a monolignol acyltransferase with either substrate versatile allylphenol or propenylphenol synthases in Escherichia coli established that various monolignol substrates were efficiently converted into their corresponding allyl/propenyl phenols, as well as providing proof of concept for efficacious conversion in a bacterial platform. This capability thus potentially provides an alternate source to these important plant phytochemicals, whether for flavor/fragrance and fine chemicals, or ultimately as commodities, e.g.; for renewable energy or other intermediate chemical purposes. Previous reports had indicated that specific and highly conserved amino acid residues 84 (Phe or Val) and 87 (Ile or Tyr) of two highly homologous allyl/propenyl phenol synthases (circa 96% identity) from a Clarkia species mainly dictate their distinct regiospecific catalyzed conversions to afford either allyl- or propenyl-phenols, respectively. However, several other allyl/propenyl phenol synthase homologs isolated by us have established that the two corresponding amino acid 84 and 87 residues are not, in fact, conserved.
- Kim, Sung-Jin,Vassao, Daniel G.,Moinuddin, Syed G.A.,Bedgar, Diana L.,Davin, Laurence B.,Lewis, Norman G.
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- Two-step, practical, and diversity-oriented synthesis of multisubstituted benzofurans from phenols through Pummerer annulation followed by cross-coupling
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Practical and diversity-oriented synthesis of multisubstituted benzofurans has been accomplished from simple phenols through a Pummerer annulation/cross-coupling sequence. Operationally simple and rapid reactions of phenols with ketene dithioacetal monoxides (KDMs) with the aid of trifluoroacetic anhydride provide the corresponding 2-methylsulfanylbenzo[b]furans. The scope of the reaction encompasses phenols and KDMs having a broad range of substituents. The remaining methylsulfanyl group in the annulation products is converted to various aryl groups through cross-coupling reactions that we improved specially to this end. This two-step approach to multisubstituted benzofurans is powerful enough to synthesize highly fluorescent benzofuran derivatives as well as the naturally occurring Eupomatenoid family.
- Murakami, Kei,Yorimitsu, Hideki,Osuka, Atsuhiro
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p. 1349 - 1366
(2015/02/19)
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- Cerium ammonium nitrate-mediated the oxidative dimerization of p-alkenylphenols: A new synthesis of substituted (±)-trans- dihydrobenzofurans
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A new method for the preparation of substituted dihydrobenzofurans is described. The p-alkenylphenols, mediated by cerium ammonium nitrate (CAN), undergo the oxidative dimerization to generate substituted dihydrobenzofurans including (±)-conocarpan, (±)-licarin A, (±)-acuminatin, as well as their related substituted dihydrobenzofurans.
- Chen, Po-Yuan,Wu, Yi-Hua,Hsu, Mon-Huei,Wang, Tzu-Pin,Wang, Eng-Chi
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p. 653 - 657
(2013/07/27)
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- Chiral phosphoric acid catalyzed inverse-electron-demand aza-Diels-Alder reaction of isoeugenol derivatives
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Highly enantio- and diastereoselective three-component inverse electron-demand aza-Diels-Alder reaction of aldehydes, anilines, and isoeugenol derivatives catalyzed by a chiral phosphoric acid catalyst are reported. A wide variety of 2,3,4-trisubstituted tetrahydroquinolines containing an aryl group at the 4-position were obtained in a one-pot process with good to high yields and excellent stereoselectivities (>95:5 dr and up to >99% ee).
- He, Long,Bekkaye, Mathieu,Retailleau, Pascal,Masson, Géraldine
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supporting information; experimental part
p. 3158 - 3161
(2012/08/07)
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- Expanding the regioselective enzymatic repertoire: Oxidative mono-cleavage of dialkenes catalyzed by Trametes hirsuta
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The first report of a biocatalytic regioselective oxidative mono-cleavage of dialkenes was successfully achieved employing a cell-free enzyme preparation from Trametes hirsuta at the expense of molecular oxygen. Selected reactions were performed on a preparative scale affording high to excellent conversions and chemoselectivities. The Royal Society of Chemistry 2012.
- Paul, Caroline E.,Rajagopalan, Aashrita,Lavandera, Ivan,Gotor-Fernandez, Vicente,Kroutil, Wolfgang,Gotor, Vicente
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supporting information; experimental part
p. 3303 - 3305
(2012/04/23)
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- MODULATORS OF G PROTEIN-COUPLED RECEPTOR 88
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The present disclosure is generally directed to compounds which can modulate G-protein coupled receptor 88, compositions comprising such compounds, and methods for modulating G-protein coupled receptor 88.
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Page/Page column 63-64
(2011/04/26)
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- Radical cation Diels-Alder cycloadditions by visible light photocatalysis
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Ruthenium(II) polypyridyl complexes promote the efficient radical cation Diels-Alder cycloaddition of electron-rich dienophiles upon irradiation with visible light. These reactions enable facile [4 + 2] cycloadditions that would be electronically mismatch
- Lin, Shishi,Ischay, Michael A.,Fry, Charles G.,Yoon, Tehshik P.
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supporting information; experimental part
p. 19350 - 19353
(2012/01/31)
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- Chavicol and Related Compounds as Nematocides
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In a search for nematocidal compounds from wild plant sources, chavicol and demethyleugenol were found from V. furcatum, and 4-vinylphenol was found from three Rosaceae species.These three compounds each contained both p-hydroxyphenyl and exo-methylene moieties, and several related compounds were prepared and tested for nematocidal activity.The results show that the hydroxyphenyl group was essential for the activity, while the aliphatic substituents on the benzene ring enhanced it.The strongest activity was found with 4-propenylphenol.
- Yoshizawa, Yuko,Kawaii, Satoru,Kanauchi, Masatoshi,Chida, Manami,Mizutani, Junya
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p. 1572 - 1574
(2007/10/02)
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- Thermal Rearrangement of 1-(3-Methylbut-2-enyloxy)-4-prop-1-enylbenzene (Feniculin): a New Synthesis of Anisoxide and Re-investigation of the Consituents of Star Anise Oil
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At 153 deg C feniculin (1) undergoes Claisen rearrangement to the 1,1-dimethylallylphenol (3), which is slowly converted into the 1,2-dimethylallylphenol (4); the products of the abnormal Claisen rearrangement, phenol (4) and anisoxide (2), are formed at
- Okely, Martyn H.,Grundon, Michael F.
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p. 897 - 899
(2007/10/02)
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