- Synthesis of the Core Structure of Palhinine A
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We present a strategy to the core structure of the alkaloid palhinine A passing through a 2,5-difunctionalized cyclohexenone. This enone was prepared by a domino Michael/aldol condensation sequence. An allylation reaction on the cyclohexenone followed by
- Gaugele, Dominik,Maier, Martin E.
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p. 2549 - 2556
(2021/06/28)
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- Selective alkyl ether cleavage by cationic bis(phosphine)iridium complexes
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Catalysts capable of heterolytic silane activation have been successfully applied to the conversion of alkyl ethers to silyl ethers via C-O bond cleavage. The previously-reported cationic pincer-supported iridium complex for this transformation suffers fr
- Jones, Caleb A. H.,Schley, Nathan D.
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supporting information
p. 1744 - 1748
(2019/02/20)
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- Photocatalyic Appel reaction enabled by copper-based complexes in continuous flow
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A copper-based photocatalyst, Cu(tmp)(BINAP)BF4, was found to be active in a photoredox Appel-type conversion of alcohols to bromides. The catalyst was identified from a screening of 50 complexes and promoted the transformation of primary and secondary alcohols to their corresponding bromides and carboxylic acids to their anhydrides. The protocol was also amendable and optimized under continuous flow conditions.
- Minozzi, Clémentine,Grenier-Petel, Jean-Christophe,Parisien-Collette, Shawn,Collins, Shawn K.
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supporting information
p. 2730 - 2736
(2018/11/21)
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- A concise stereoselective synthesis of (+)-1-deoxy-6-epi-castanospermine
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A concise stereoselective synthesis of (+)-1-deoxy-6-epi-castanospermine has been developed through stereoselective approach from the chiral precursor R-Glycidol. The key steps in the synthesis involve Grignard reaction through Weinreb amide, followed by Sharpless dihydroxylation and stereoselective reduction of imine assigned the required stereochemical feature of indolizidine azasugar (+)-1-deoxy-6-epi-castanospermine.
- Gajare, Vikas S.,Khobare, Sandip R.,Datrika, Rajender,Reddy, K. Srinivasa,Rajana, Nagaraju,Babu, B. Kishore,Rao, B. Venkateswara,Syam Kumar
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supporting information
p. 1486 - 1488
(2016/03/12)
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- Light-mediated deoxygenation of alcohols with a dimeric gold catalyst
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A new protocol for the reductive deoxygenation of primary alcohols was explored. This photo-mediated method combines a novel approach to bromination of alcohols merged with the powerful reducing capability of [Au2(dppm)2]Cl2 [dppm = 1,1-bis(diphenylphosphino)methane] as a photoredox catalyst. The highly efficient methods discussed are marked by the use of UVA light-emitting diodes, which have significantly reduced reaction times and lowered setup cost.
- McCallum, Terry,Slavko, Ekaterina,Morin, Mathieu,Barriault, Louis
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supporting information
p. 81 - 85
(2015/02/18)
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- Synthetic studies on lycopodine: Construction of hexahydrojulolidine core by intramolecular Mannich reaction
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The tricyclic core skeleton of lycopodine was constructed by the intramolecular Mannich reaction of a 12-membered cyclic amine. The concise assembly of the macrocyclic intermediate was executed by the sequential inter- and intramolecular N-alkylation of a
- Sato, Takanao,Ueda, Hirofumi,Tokuyama, Hidetoshi
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supporting information
p. 7177 - 7180
(2015/01/09)
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- Syntheses of the Stemona alkaloids (±)-stenine, (±)- neostenine, and (±)-13-epineostenine using a stereodivergent Diels-Alder/azido-Schmidt reaction
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A tandem Diels-Alder/azido-Schmidt reaction sequence provides rapid access to the core skeleton shared by several Stemona alkaloids including stenine, neostenine, tuberostemonine, and neotuberostemonine. The discovery and evolution of inter- and intramole
- Frankowski, Kevin J.,Golden, Jennifer E.,Zeng, Yibin,Lei, Yao,Aube, Jeffrey
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p. 6018 - 6024
(2008/09/20)
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- BORON-CONTAINING SMALL MOLECULES
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This invention provides, among other things, novel compounds useful for treating bacterial infections, pharmaceutical compositions containing such compounds, as well as combinations of these compounds with at least one additional therapeutically effective agent.
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Page/Page column 220
(2009/01/23)
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- A combined intramolecular Diels-Alder/intramolecular Schmidt reaction: Formal synthesis of (±)-stenine
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Four stereocenters and three rings are established in one step in a new formal synthesis of (±)-stenine (see scheme). This key reaction cascade consists of an intramolecular Diels-Alder reaction followed by an intramolecular Schmidt reaction. The resultin
- Golden, Jennifer E.,Aube, Jeffrey
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p. 4316 - 4318
(2007/10/03)
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- Etherification of alkoxydialkylsilanes with carbonyl compounds
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A novel method for preparing ethers from alkoxydialkylsilanes and carbonyl compounds through reductive etherification is described. The salient feature in this method is the utilization of internal hydrogen as the hydride source for reducing the oxonium intermediate generated by using the Cl(R)2SiBr[BiBr3/Cl(R)2SiH] catalytic system.
- Jiang, Xinglong,Bajwa, Joginder S,Slade, Joel,Prasad, Kapa,Repi?, Oljan,Blacklock, Thomas J
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p. 9225 - 9227
(2007/10/03)
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- S,S-dimethyl dithiocarbonate: A novel carbonyl dication synthon in the synthesis of ketones
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We report herein the use of DMDTC as an effective carbonyl dication equivalent in ketone synthesis. According to our strategy, we also successfully devised a synthetic pathway for S-methyl (trimethylsilyl)thioacetate which may be a potentially useful synthetic reagent in organic synthesis.
- Chen, Chiar-Dy,Huang, Jui-Wen,Leung, Man-Kit,Li, Huei-Hsu
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p. 9067 - 9078
(2007/10/03)
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- Formation of bridge-methylated decalins by antibody-catalyzed tandem cationic cyclization
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We report the antibody catalysis of an electrophilic tandem ring forming process that yields a bicyclic ring system at neutral pH. Three closely related decalin systems that represent rings A and B of the steroid nucleus account for 50% of the overall pro
- Hasserodt, Jens,Janda, Kim D.,Lerner, Richard A.
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p. 5993 - 5998
(2007/10/03)
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- The Synthesis of Bridged Oligophenylenes from Fluorene 1. Terphenyls and Quaterphenyls
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Improved methods are presented for the alkylation of fluorene (2) to 9,9- dialkylfluorenes (3-6) free from 9-monoalkylfluorenes.Mono- and dihalogenated derivatives of 2-6 are reported as are a variety of ring substituted 9,9-dialkylfluorenes.Halogenated 9,9-dialkylfluorenes and aryl or methyl Grignard reagents were cross-coupled in Pd-catalyzed reactions to generate a series of novel p-oligophenylenes (four terphenyls (26, 27, 29 and 31c) and nineteen quterphenyls (33-6, 64-71 and 73-79)) each possessing one or two dialkylated methylene bridges between aromatic rings.Each bridged oligophneylene showed enhanced solubility, high quantum efficiency and photochemical stability.A number of quaterphenyls incorporated substituents which extended the conjugation of the oligophenylene chromophore.
- Kelley, Charles J.,Ghiorghis, Alem,Kauffman, Joel M.
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p. 2701 - 2733
(2007/10/03)
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- Folding strain stereocontrol in cyclohexane ring formation by means of an intramolecular ester enolate alkylation reaction
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Diastereoselectivity in the cyclization of ethyl 7-bromo-2-methylheptanoates with an additional substituent at various positions in the chain, by LDA treatment, was investigated in connection with the concept of folding strain stereocontrol. Cyclization of 3-, 4-, and 6-methyl-substituted substrates revealed high selectivity, which demonstrates the prevalence of folding strain stereocontrol and the usefulness of this approach for stereoselective ring construction. In particular, reactions of the latter two substrates resulted in the stereodivergent preparation of diastereomeric 1,3-dimethylcyclohexanecarboxylates. In the case of the 5-methyl-substituted substrate, the selectivity of ring closure was only moderate. 1H and 13C NMR spectroscopic data were useful for determining the conformation of 1-methylcyclohexanecarboxylate derivatives. The origin of the diastereoselectivity was examined through the qualitative comparison of the strain in the diastereomeric folding in the transition state. Various factors that might affect stereoselectivity were examined in the cyclization of 5-substituted substrates to better understand this concept. As predicted, the selectivity increased as the substituent became bulkier: Ph Me ≈ Et ≤ i-Pr t-Bu. The effects of other factors - solvent, base counter cation, and leaving group - on selectivity agree with results predicted from the reactivity-selectivity relationship.
- Tokoroyama, Takashi,Kusaka, Hisashi
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p. 2487 - 2502
(2007/10/03)
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- Synthesis of carbazole derivatives, II: C-2-substituted indoles as intermediates of pyrrolino[3,4-c]carbazoles
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Starting from the indole derivatives 4, 7 and 15 Grignard reaction, nucleophilic substitution at the pertinent dithian, and Wittig reaction afford preparatively useful side chains. By intramolecular Michael reaction the pertinent compounds lead to the pyr
- Mahboobi,Kuhr
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- 9-(SULFOXIMINOALKYL)GUANINE NUCLEOSIDES AS POTENTIAL ANTIHERPETIC AGENTS
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A novel series of guanine nucleoside analogues 5-8 which contain a C-terminal sulfoximine have been synthesized.Key features of the synthesis include 1) the successful application of the trifluoroacetyl functional group as a stable, base-labile protecting group for the sulfoximine nitrogen and 2) the Mitsunobu-type coupling of alcohols 14 and 18-20 with purine 15.
- Dolle, Roland E.,McNair, David
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p. 133 - 136
(2007/10/02)
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- Synthesis of α-Hydroxy Ketones by Samarium(II) Iodide-Mediated Coupling of Organic Halides, an Isocyanide, and Carbonyl Compounds
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A new strategy for the synthesis of α-hydroxy ketones by samarium(II) iodide-mediated three-component coupling of organic halides, an isocyanide, and carbonyl compounds is disclosed.An (α-iminoalkyl)samarium(III) species is generated in situ by treatment
- Murakami, Masahiro,Kawano, Teiji,Ito, Hajime,Ito, Yoshihiko
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p. 1458 - 1465
(2007/10/02)
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- The Synthesis of Octacidomycin
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The total synthesis of octacidomycin (1), a novel oligocarboxylic acid antibiotic, and some shorter new model acids (19, 21, 24) is described.Key compounds in a series of fragment condensations of C19-, C5- and C2-units are α,α'-bis(bromopentyl)-substituted azealic- (6) and 3-(benzyloxypropyl)malonic esters (7).A six step synthesis yields bacteriostatically active octacidomycin (14=1). 14 and its octamethyl ester 15 are identical with the native products in all chemical and spectroscopic properties.Further combinations of fragments give tri-, tetra-, and pentacarboxylic acids.These demonstrate the flexibility of this widely variable synthetic method leading to new carboxylic acids and hydrocarbons.
- Kerber, Karl-Heinz,Lackner, Helmut
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p. 719 - 726
(2007/10/02)
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- Total Synthesis of Lycopodium Alkaloids: (+/-)-Lycopodine, (+/-)-Lycodine, and (+/-)-Lycodoline
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Intramolecular Mannich condensation is shown to be a powerful method for the synthesis of lycopodium alkaloids (eq 2).Two syntheses of (+/-)-lycopodine (1) have been developed.In the first (Scheme II), compound 1 is produced in 13 steps from 5-methyl-1,3-cyclohexanedione (16.6percent overall yield).In this synthesis, rings A and B are formed in the Mannich cyclization, and ring D is closed by aldol condensation.The alternative lycopodine synthesis (Scheme IV) is more convergent and produces (+/-)-1 in only eight operations from the same starting point (13percent overall yield).In this synthesis, primary amine 41 is employed in the Mannich reaction, and ring D is closed by intramolecular alkylation or a bromo amine.The synthesis of (+/-)-lycodine (3) also requires eight steps and provides the alkaloid in 13.2percent overall yield (Scheme V).This synthesis features an efficient, one-pot conversion of δ,ε-unsaturated ketone 46 into pyridine 3. (+/-)-Lycodoline (3) is produced by an 11-step route in 3.2percent overall yield as shown in eq 16, 18, and 22.In this synthesis, the angular hydroxyl is introduced by the stereoselective autoxidation of an octahydroquinone (eq.16).The Mannich cyclization is completed by a novel method which utilizes the base-catalyzed polymerization of 3-bromo-1-propanol as a method for slow delivery of HBr, thus allowing the reaction to be carried out under essentially neutral conditions (eq.18).The lycodoline synthesis is completed by use of a novel variant of the Oppenauer oxidation (61 -> 62).
- Heathcock, Clayton H.,Kleinman, Edward F.,Binkley, Edward S.
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p. 1054 - 1068
(2007/10/02)
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- MECHANISMUS DER PROTONKATALYSIERTEN GASPHASENDEHYDRATISIERUNG VON FURFURYLALKOHOL
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The gas phase proton catalysed water elimination of tetrahydrofurfuryl alcohol (1) gives exclusively the ring-enlarged oxonium-ion 12.There is no experimental indication for the generation of 11 via a -hydrogen migration.From the analysis of appropriately 13C-labelled precursors in combination with collisional activation mass spectrometry the mechanism for the ring-enlargement has been derived, clearly indicating that the oxygen/carbon bond is cleaved.A comparison of the experimental results with computational investigation (ab initio molecular orbital calculations at the 4-31G level) suggests that free tetrahydrofurfuryl cation 7 is not generated in the gas phase solvolysis.The elimination of H2O from the protonated molecule of 1 is a process characterised by anchimeric assistance of the ether oxygen 15.
- Thies, H.,Wolfschuetz, R.,Frenking, G.,Schmidt, J.,Schwarz, H.
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p. 1647 - 1656
(2007/10/02)
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- 11,12-Secoprostaglandins
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This invention relates to 11,12-secoprostaglandins and processes for their manufacture. These compounds have prostaglandin-like biological activity and are particularly useful as renal vasodilators, for the treatment of hypertension, for the prevention of thrombus formation, in preventing gastric secretion, and as regulators of the immune response.
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