- Enantioselective Total Synthesis of Berkeleyone A and Preaustinoids
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Herein we report the first enantioselective total synthesis of 3,5-dimethylorsellinic acid-derived meroterpenoids (?)-berkeleyone A and its five congeners ((?)-preaustinoids A, A1, B, B1, and B2) in 12–15 steps, starting from commercially available 2,4,6-trihydroxybenzoic acid hydrate. Based upon the recognition of latent symmetry within D-ring, our convergent synthesis features two critical reactions: 1) a symmetry-breaking, diastereoselective dearomative alkylation to assemble the entire carbon core, and 2) a Sc(OTf)3-mediated sequential Krapcho dealkoxycarbonylation/carbonyl α-tert-alkylation to forge the intricate bicyclo[3.3.1]nonane framework. We also conducted our preliminary biomimetic investigations and uncovered a series of rearrangements (α-ketol, α-hydroxyl-β-diketone, etc.) responsible for the biomimetic diversification of (?)-berkeleyone A into its five preaustinoid congeners.
- Franzoni, Ivan,Guo, Chuning,Hong, Benke,Ji, Yunpeng,Jia, Hongli,Li, Houhua,Zhang, Yang
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supporting information
p. 14869 - 14874
(2021/05/27)
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- COMBINATION TREATMENT OF BACTERIAL INFECTION
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The present invention resides in the discovery that combined use of kuraridin (or any one of its analogs) and epicatechin gallate (ECG) can provide heightened level of antimicrobial activity, especially for the suppression of bacteria of the Staphylococcus aureus and Staphylococcal species. Compositions, kits, and methods for the combination use are disclosed.
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Paragraph 0115; 0116
(2020/06/08)
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- Biomimetic Synthesis of Complex Flavonoids Isolated from Daemonorops “Dragon's Blood”
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The dragonbloodins are a pair of complex flavonoid trimers that have been isolated from the palm tree Daemonorops draco, one of the sources of the ancient resin known as “dragon's blood”. We present a short synthesis that clarifies their relative configur
- Schmid, Matthias,Trauner, Dirk
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supporting information
p. 12332 - 12335
(2017/09/25)
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- A Strategy toward the Biomimetic Synthesis of (±)-Morusalbanol A Pentamethyl Ether
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A strategy toward the biomimetic synthesis of morusalbanol A pentamethyl ether is described. The synthesis is based on a hydrogen-bond-assisted Diels-Alder cycloaddition between a dehydroprenyl diene and a chalcone dienophile. Selective cleavage of the ortho-methyl ether of the resulting cycloadduct allows rotation of the C3-C21 bond and subsequent intramolecular cyclization affords the pentamethyl ether of (±)-morusalbanol A. As with the natural product, morusalbanol A, a number of key proton and carbon signals are absent in the NMR spectra of the title product.
- Tee, Jia Ti,Keane, Theo,Meijer, Anthony J. H. M.,Khaledi, Hamid,Rahman, Noorsaadah Abd,Chee, Chin Fei
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p. 2263 - 2270
(2016/07/15)
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- Total Synthesis and Biological Evaluation of Irciniastatin A (a.k.a. Psymberin) and Irciniastatin B
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Irciniastatin A (a.k.a. psymberin) and irciniastatin B are members of the pederin natural product family, which have potent antitumor activity and structural complexity. Herein, we describe a full account of our total synthesis of (+)-irciniastatin A and (-)-irciniastatin B. Our synthesis features the highly regioselective Eu(OTf)3-catalyzed, DTBMP-assisted epoxide ring opening reaction with MeOH, which enabled a concise synthesis of the C1-C6 fragment, extensive use of AZADO (2-azaadamantane N-oxyl) and its related nitroxyl radical/oxoammonium salt-catalyzed alcohol oxidation throughout the synthesis, and a late-stage assembly of C1-C6, C8-C16, and C17-C25 fragments. In addition, for the synthesis of (-)-irciniastatin B, we achieved the C11-selective control of the oxidation stage via regioselective deprotection and AZADO-catalyzed alcohol oxidation. The synthetic irciniastatins showed high levels of cytotoxic activity against mammalian cells. Furthermore, chemical footprinting experiments using synthetic compounds revealed that the binding site of irciniastatins is the E-site of the ribosome.
- Uesugi, Shun-Ichiro,Watanabe, Tsubasa,Imaizumi, Takamichi,Ota, Yu,Yoshida, Keisuke,Ebisu, Haruna,Chinen, Takumi,Nagumo, Yoko,Shibuya, Masatoshi,Kanoh, Naoki,Usui, Takeo,Iwabuchi, Yoshiharu
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p. 12333 - 12350
(2016/01/09)
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- Synthesis of 8-desmethoxy psymberin: A putative biosynthetic intermediate towards the marine polyketide psymberin
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The synthesis of a putative biosynthetic precursor of psymberin including a formal synthesis of the natural product is described. The key step towards the densely functionalized tetrahydropyran core was an enantioselective catalytic Mukaiyama aldol reacti
- Bielitza, Max,Pietruszka, J?rg
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p. 8300 - 8308
(2013/07/25)
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- Access to resorcylic acid lactones via phosphonate based intramolecular olefination
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An approach to resorcylic acid lactones is described, exploiting an intramolecular olefination reaction for the generation of the 14-membered macrolactone. The synthetic route gave zearalenone precursors, and the preparations of other RAL analogues, trans
- Napolitano, Carmela,McArdle, Patrick,Murphy, Paul V.
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scheme or table
p. 7404 - 7407
(2011/02/22)
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- Studies on the total synthesis of lactonamycin: Synthesis of the CDEF ring system
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A concise and efficient synthesis of the tetracyclic CDEF ring system of lactonamycin (1) is described. The key step involved the Lewis acid mediated, intramolecular Friedel-Crafts acylation of carboxylic acid 6 to produce the tetracyclic CDEF core struct
- Wehlan, Hermut,Jezek, Eva,Lebrasseur, Nathalie,Pave, Gregoire,Roulland, Emmanuel,White, Andrew J. P.,Burrows, Jeremy N.,Barrett, Anthony G. M.
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p. 8151 - 8158
(2007/10/03)
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- A one-pot synthesis and X-ray crystallographic and computational analyses of methyl-2,4-dimethoxysalicylate - A anti-tumour agent
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The thermal decarboxylation of 2-methoxycarbonyl-5-(4′-nitrophen-oxy) tetrazole (1a) with the electron-rich, aromatic compounds (anisole, N,N-dimethylaniline, 1,4-dimethoxybenzene, and 1,3,5-trimethoxybenzene), neat or in polar solvents (DMSO, DMF, and CH3CN), is investigated. The solid phase thermal decomposition of a mixture of 1a, 1,3,5-trimethoxybenzene, and a Lewis acid (AlCl3) produces methyl-2,4-dimethoxysalicylate (8) in good yield, instead of the expected 2,4,6-trimethoxybenzoic acid. The X-ray structure of 8 shows intramolecular hydrogen bonds between the carbonyl oxygen and hydrogens of Me and OH groups. A measured pKa value of 6.8 compares well with a value of 6.4 estimated using the [C=O...H...O] hydrogen bond distances.
- Dabbagh, Hossein A.,Noroozi-Pesyan, Nader,Patrick, Brian O.,James, Brian R.
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p. 1179 - 1185
(2007/10/03)
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- Synthesis of 3-arylisocoumarins, including thunberginols A and B, unsymmetrical 3,4-disubstituted isocoumarins, and 3-ylidenephthalides via iodolactonization of methyl 2-ynylbenzoates or the corresponding carboxylic acids
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3-Aryl-4-iodoisocoumarins, which were readily and efficiently prepared by regioselective iodolactonization of methyl 2-ynylbenzoates or the corresponding carboxylic acids, were used as precursors either to 3-arylisocoumarins, including naturally-occurring
- Rossi, Renzo,Carpita, Adriano,Bellina, Fabio,Stabile, Paolo,Mannina, Luisa
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p. 2067 - 2081
(2007/10/03)
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- Radical-capturing reaction of 5,7,3′,4′-tetramethylquercetin with the AIBN radical initiator
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In order to clarify the mechanism for the radical-capturing reaction which is initiated at the C3-hydroxyl group of flavonols, 5,7,3′,4′-tetramethylquercetin (TMQ) was reacted with the 2,2′-azobis-isobutyronitrile (AIBN) radical initiator in benzene. Six products, one depside and its two hydrolytic products, one nitrite adduct, and two others, were isolated from the reaction mixture, and their structures were determined by instrumental analyses. The quantitative change to the four main products against the reaction time was measured by an HPLC method. The radical-capturing reaction pathway for TMQ with AIBN is proposed from these products and their quantitative changes. The pathway dividing into two clearly reveals that one subpath formed the depside and its hydrolytic products, while the other formed the nitrite adduct. The reactivity of each two sub-path was nearly the same, different from the case of TMQ and the 2,2′-azobis-2,4-dimethylvaleronitrile (AMVN) radical initiator.
- Ishikawa, Takahiro,Takagi, Michiyo,Kanou, Mamiko,Kawai, Shingo,Ohashi, Hideo
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p. 173 - 177
(2007/10/03)
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- Substituent Effects on the Photorearrangements of 4-Alkoxy-4-carbomethoxy-3-methoxy-2,5-cyclohexadien-1-ones
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Enantiomerically enriched 4-carbomethoxy-3,4-dimethoxy-2,5-cyclohexadien-1-one (1) undergoes a completely diastereoselective (but not enantiospecific) type A photorearrangement at 366 nm to give 6-carbomethoxy-4,6-dimethoxybicyclohex-3-en-2-one (2) in 81 percent isolated yield.A chiral NMR shift study indicates that 1 undergoes partial loss of absolute configuration at C(4) during irradiation.Bicyclohexenone 2 is photostable at 366 nm but rearranges to its diastereoisomer 3 and phenols 4 and 5 at > 300 nm.It is proposed that ground-state conformational effects control the type A photoreactivity of 1 and that rearrangement to 2 occurs in accord with the principle of least motion in the transition states for rearrangements to diastereomerically related zwitterions 1a and 1b (Scheme III).The intramolecular 2 + 2 photocycloaddition of 4-carbomethoxy-3-methoxy-4-(1'-oxa-3'-butenyl)-2,5-cyclohexadien-1-one (9) gives a mixture of 7-oxatricyclodecenones 10 (58percent) and 11 (18percent), without interference from type A photoreactivity.
- Schultz, Arthur G.,Harrington, Roger E.
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p. 6391 - 6394
(2007/10/02)
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- Trimethoxyphenyl Compounds, XI. Constituents of Hagenia abyssinica, 2: Synthesis of Phloracylophenones Containing One Phloroglucinol Unit
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For the Koso constituents K6 and K8, we previously proposed the structures 1a, b and 2a, b.These assignments have been confirmed by synthesis. - Keywords: Flores koso, Revised Structure, Synthesis of Phloroglucinols
- Schiemenz, Guenter Paulus,Behrens, Heinz,Ebert, Claus Peter,Maienschein, Konrad,Schroeder, Jens-Michael
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p. 681 - 692
(2007/10/02)
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