- Total Synthesis and Structure Revision of a Fungal Glycolipid Fusaroside
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Herein, we report a strategy for the total synthesis of a structurally unique fungal glycolipid fusaroside. The first total synthesis of the proposed structure involved construction of the complex, branched lipid chain having a variety of alkenes with E stereochemistry and attachment of the masked α,β-unsaturated β-keto acid at the O-4 position of trehalose as key steps. We propose a revision in the structure of fusaroside, particularly the position of olefins in the lipid chain.
- Jana, Santanu,Sarpe, Vikram A.,Kulkarni, Suvarn S.
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- Radical cyclization using a thioacetal group for radical generation
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The generation and cyclization of several heterocyclic radicals were investigated. The hydrogen abstraction from 1,3-dithiane, 1,3-dithiolane, and 1,3-oxathiane rings by a benzophenone triplet generated the corresponding heterocyclic radicals, which gave the cyclized products by intramolecular addition to α,β-unsaturated esters. Diastereoselective radical cyclization using chiral acetals was also investigated.
- Nishida, Atsushi,Kawahara, Norio,Nishida, Mayumi,Yonemitsu, Osamu
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- Oxygenated N-Acyl Alanine Methyl Esters (NAMEs) from the Marine Bacterium Roseovarius tolerans EL-164
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The marine bacterium Roseovarius tolerans EL-164 (Rhodobacteraceae) can produce unique N-acylalanine methyl esters (NAMEs) besides strucutrally related N-acylhomoserine lactones (AHLs), bacterial signaling compounds widespread in the Rhodobacteraceae. The structures of two unprecedented NAMEs carrying a rare terminally oxidized acyl chain are reported here. The compounds (Z)-N-16-hydroxyhexadec-9-enoyl-l-alanine methyl ester (Z9-16-OH-C16:1-NAME, 3) and (Z)-N-15-carboxypentadec-9-enoyl-l-alanine methyl ester (16COOH-C16:1-NAME, 4) were isolated, and the structures were determined by NMR and MS experiments. Both compounds were synthesized to prove assignments and to test their biological activity. Finally, non-natural, structurally related Z9-3-OH-C16:1-NAME (18) was synthesized to investigate the mass spectroscopy of structurally related NAMEs. Compound 3 showed moderate antibacterial activity against microorganisms such as Bacillus, Streptococcus, Micrococcus, or Mucor strains. In contrast to AHLs, quorum-sensing or quorum-quenching activity was not observed.
- Bruns, Hilke,Herrmann, Jennifer,Müller, Rolf,Wang, Hui,Wagner D?bler, Irene,Schulz, Stefan
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- Formation of isomerized E,Z-configured 1,3-dienes in construction of macrocyclic trienes by diene-ene RCM
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Construction of macrocyclic trienes by diene-ene RCM of tetraenes was examined. In the reactions, macrocyclic trienes were obtained as a mixture of two isomers with E,Z-configured 1,3-diene moiety. The formation of two isomers can be understandable by the
- Takagi, Ryukichi,Tanaka, Kenji,Yamamoto, Koumei,Hiraga, Yoshikazu,Kojima, Satoshi,Abe, Manabu
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- Total Synthesis of Resolvin T4
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A total synthesis of resolvin T4 was achieved by connecting three intermediates by Wittig reactions. The enal in the C1 C10 part was constructed through reduction of a propargylic alcohol with Red-Al followed by oxidation. The enal moiety in the C11 C16 part was synthesized by a ring-opening reaction of a silyl epoxide followed by a Peterson elimination. The chiral centers at C7 and C13 were constructed by ruthenium-catalyzed asymmetric transfer hydrogenation.
- Arai, Kohei,Kobayashi, Yuichi,Ogawa, Narihito
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supporting information
p. 76 - 79
(2021/11/30)
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- Synthesis of C37-Alkenones for Past Climate Reconstructions
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The total syntheses of three C37 methyl-alkenones with different degrees of unsaturation and of their 13C-labelled analogues from commercially available starting materials are presented herein for the first time. These molecules are important to improve the reliability of the measurements and reconstructions of the sea surface temperature and salinity.
- Berton, Giacomo,Pizzini, Sarah,Fabris, Fabrizio,Bertolin, Tommaso,Pafumi, Eugenia,Ceccon, Leonardo,Daelemans, Jonas,Borsato, Giuseppe,Scarso, Alessandro,Piazza, Rossano,Ferretti, Patrizia
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p. 3542 - 3551
(2020/03/26)
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- Red-light-mediated BartonMcCombie reaction
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A red-light-mediated BartonMcCombie reaction is described, in which chlorophyll a is used as a photocatalyst and tris(trimethylsilyl)silane or Hantzsch ester is used as the hydrogen source. The reaction can be performed with a set of easily available equipment and reagents, and a variety of linear and cyclic xanthates could be applied. In contrast to the traditional conditions, the reaction does not involve toxic organotin or an explosive radical initiator. The reaction mechanism was analyzed both by experiments and computation, and it was suggested that the radical chain mechanism initiated by excitation of complex followed by charge transfer is likely to be operative.
- Ichii, Naoki,Ogura, Akihiro,Shibata, Kouhei,Takao, Ken-Ichi
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supporting information
p. 936 - 941
(2020/11/09)
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- Catalyst-Controlled Diastereoselective Synthesis of Cyclic Amines via C-H Functionalization
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Reliable regio- and stereochemical techniques applicable to nonactivated aliphatic systems remain largely elusive due to the challenges of discriminating between multiple, relatively strong sp3 C-H bonds whose chemical behavior often differ onl
- Munnuri, Sailu,Adebesin, Adeniyi Michael,Paudyal, Mahesh P.,Yousufuddin, Muhammed,Dalipe, Alfonso,Falck, John R.
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supporting information
p. 18288 - 18294
(2017/12/27)
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- Hexanes/acetonitrile: A binary solvent system for the efficient monosilylation of symmetric primary and secondary diols
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Symmetric diols are useful compounds in the synthesis of natural products, their value often dependent on their successful monoprotection. A general and simple method for the monosilylation of symmetrical primary and secondary diols is reported. The metho
- Wilke, Burkhardt I.,Dornan, Mark H.,Yeung, Jon,Boddy, Christopher N.,Pinto, Atahualpa
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p. 2600 - 2602
(2014/05/06)
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- Asymmetric synthesis of 3,3,5,5-tetrasubstituted 1,2-dioxolanes: Total synthesis of epiplakinic acid F
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The first enantioselective total synthesis of epiplakinic acid F (1) was achieved through a pivotal step involving a radical-mediated asymmetric peroxidation of vinylcyclopropanes with molecular oxygen to construct highly substituted 1,2-dioxolanes. Subsequent conversions of the chiral 1,2-dioxolanes led to total synthesis of epiplakinic acid F (1) and the confirmation of its absolute configuration. The enantiomer of epiplakinic acid F methyl ester (2) was also prepared. This journal is the Partner Organisations 2014.
- Tian, Xiang-Yin,Han, Jian-Wei,Zhao, Qiong,Wong, Henry N. C.
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p. 3686 - 3700
(2014/06/09)
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- Vicinal bisheterocyclizations of alkynes via nucleophilic interception of a catalytic platinum carbene
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A novel platinum-catalyzed double heterocyclization of propargylic ethers is described. The transformation exploits the intermediacy of a key α,β-unsaturated carbene. The reactivity of this carbene is such that systems can be developed which avoid a complicating 1,2-hydrogen migration, allowing remarkable versatility in the selective syntheses of oxygen- and nitrogen-containing vicinal bis-heterocyclic compounds.
- Allegretti, Paul A.,Ferreira, Eric M.
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supporting information
p. 17266 - 17269
(2014/01/06)
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- Tandem hydroformylation/hydrogenation of alkenes to normal alcohols using Rh/Ru dual catalyst or Ru single component catalyst
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The catalyst system for tandem hydroformylation/hydrogenation of terminal alkenes to the corresponding homologated normal alcohol was developed. The reaction mechanism for the Rh/Ru dual catalyst was investigated by real-time IR monitoring experiments and 31P NMR spectroscopy, which proved the mutual orthogonality of Rh-catalyzed hydroformylation and Ru-catalyzed hydrogenation. Detailed investigation about Ru-catalyzed hydrogenation of undecanal under H2/CO pressure clarified different kinetics from the hydrogenation under H2 and gave a clue to design more active hydrogenation catalysts under H2/CO atmosphere. The solely Ru-catalyzed normal selective hydroformylation/hydrogenation is also reported.
- Takahashi, Kohei,Yamashita, Makoto,Nozaki, Kyoko
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supporting information
p. 18746 - 18757
(2013/01/15)
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- Cyclization reactions through DDQ-mediated vinyl oxazolidinone oxidation
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Vinyl oxazolidinones react with DDQ to form α,β-unsaturated acyliminium ions in a new method for forming electrophiles under oxidative conditions. Appended nucleophiles undergo 1,4-addition reactions with these intermediates to form cyclic vinyl oxazolidinones with good levels of diastereocontrol, highlighting a new approach to utilizing oxidative carbon-hydrogen bond functionalization to increase molecular complexity.
- Liu, Lei,Floreancig, Paul E.
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supporting information; scheme or table
p. 3152 - 3155
(2009/12/05)
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- Synthesis of the C1-C52 fragment of amphidinol 3, featuring a β-alkoxy alkyllithium addition reaction
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(Chemical Equation Presented) An advanced intermediate for the synthesis of amphidinol 3 has been prepared. A cross-metathesis reaction was used to couple the C1-C12 and C13-C26 segments. An unusual β-alkoxy alkyllithium reagent was generated from this se
- Huckins, John R.,De Vicente, Javier,Rychnovsky, Scott D.
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p. 4757 - 4760
(2008/03/14)
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- Catalytic glycosylation with rhodium(III)-triphos catalysts
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The formation of glycosides in high yield from 1-hydroxy sugars using catalytic amounts (0.5molpercent) of Rh(III)Cl3(triphos) (1a) or [Rh(III)(MeCN)3(triphos)](TfO)3 (1b) is described. High stereocontrol at the anomeric c
- Wagner, Beatrice,Heneghan, Michael,Schnabel, Gerhard,Ernst, Beat
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p. 1303 - 1306
(2007/10/03)
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- Syntheses and biological evaluation of vinblastine congeners.
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Sixty-two congeners of vinblastine (VLB), primarily with modifications of the piperidine ring in the carbomethoxycleavamine moiety of the binary alkaloid, were synthesized and evaluated for cytotoxicity against murine L1210 leukemia and RCC-2 rat colon cancer cells, and for their ability to inhibit polymerization of microtubular protein at 10(7) M concentrations was found for L1210 inhibition by these compounds, with the most active 1000x as potent as vinblastine.
- Kuehne, Martin E,Bornmann, William G,Marko, Istvan,Qin, Yong,LeBoulluec, Karen L,Frasier, Deborah A,Xu, Feng,Mulamba, Tshilundu,Ensinger, Carol L,Borman, Linda S,Huot, Anne E,Exon, Christopher,Bizzarro, Fred T,Cheung, Julia B,Bane, Susan L
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p. 2120 - 2136
(2007/10/03)
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- Dimethylthiocarbamate (DMTC): An Alcohol Protecting Group
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(Equation Presented) Dimethylthiocarbamates (DMTCs), prepared from the corresponding alcohols using commercial dimethylthiocarbamoyl chloride, are spectrally simple, achiral, and nonpolar. DMTCs are moderately to highly stable to a wide range of reagents and conditions including metal hydrides, hydroboration, ylides, NaOH, HCl, organolithiums, Grignards, DDQ, PCC, Swern, n-Bu4NF, CrCl2, heat, and Lewis acids. They are readily removed by NalO4 or H2O2 in the presence of other common alcohol protecting groups.
- Barma,Bandyopadhyay,Capdevila, Jorge H.,Falck
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p. 4755 - 4757
(2007/10/03)
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- Highly efficient deacetylation by use of the neutral organotin catalyst [tBu2SnOH(Cl)]2
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Deprotection of acetyl esters is effected cleanly by the neutral organotin catalyst, [tBu2SnOH(Cl)]2. The mildness of the reaction gives rise to great synthetic versatility and in the process a variety of functional groups are tolerated. Differentiations between primary, secondary, and tertiary alcohols and between acetyl ester and other esters are feasible. No racemization occurs with chiral acetyl esters. Exclusive deprotection of primary acetyl esters in carbohydrates and nucleosides is observed. The crude product thus obtained can be used for further reactions without purification.
- Orita, Akihiro,Hamada, Yuuki,Nakano, Takehiko,Toyoshima, Shinji,Otera, Junzo
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p. 3321 - 3327
(2007/10/03)
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- Stereoselective transannular radical cyclization of unsaturated cyclic iodoacetals yielding medium-sized carbocycles
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Iodoacetalization of (Z)-allylic alcohols 1a-1c in high dilution followed by transannular radical cyclization gave cis-fused bicyclic acetals 5a-5c and 6a-6c with high diastereoselectivities (84-93% de) and in 54-62% yields. The reaction of 2a gave 5a and 6a with 77% de, but in low yield. However, the sequential reaction of the higher homologue 1d and (E)-allylic alcohols 2b-2d showed poor diastereoselectivities.
- Nagano,Tada,Isobe,Yajima
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p. 1193 - 1195
(2007/10/03)
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- [tBu2SnOH(CI)]2 as a highly efficient catalyst for deacetylation
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The title compound effects deacetylation of acetates under almost neutral conditions. A variety of functional groups are tolerated and high selectivities are attained in competitions between primary, secondary, and tertiary alcohol acetates. Thieme Stuttgart.
- Orita, Akihiro,Sakamoto, Katsumasa,Hamada, Yuuki,Otera, Junzo
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p. 140 - 142
(2007/10/03)
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- A novel, simple and rapid regeneration of alcohols from their allylic ethers using NaCNBH3/TMSCl
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A Novel, Simple and efficient method for the regeneration of alcohols from their allylic ethers using NaCNBH3/TMSCl is described.
- Venkat Rao,Subbash Reddy,Hari Mohan,Iyengar
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p. 3565 - 3568
(2007/10/03)
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- Studies towards the synthesis of the marine metabolite, octalactin A
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Studies towards the synthesis of the marine metabolite octalactin A 1, are described. Key steps in this strategy include an anti aldol reaction to set the C(r)C(s) stereochemistry, Horner Wadsworth Emmons coupling to give the trisubstituted E-double bond and a novel samarium-mediated cyclisation reaction.
- Hulme, Alison N.,Howells, Garnet E.
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p. 8245 - 8248
(2007/10/03)
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- A novel, mild and facile reductive cleavage of allyl ethers by NaBH4/I2 system
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A simple and efficient method for the deprotection of allyl ethers using NaBH4/I2 system is described.
- Thomas, R. Mathew,Mohan, G. Hari,Iyengar
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p. 4721 - 4724
(2007/10/03)
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- A mild, convenient, Non-Acidic conversion of enol ethers into alcohols using Hg(OAc)2 - NaBH4
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Alkyl enol ethers can be converted into the corresponding alcohols in good to excellent yields by treatment with aqueous Hg(OAc)2 - NaBH4 in one reaction flask. This method is sufficiently mild to allow the survival of acid-sensitive groups such as silyl ethers, THP-protected alcohols and N-Boc-protected amines.
- Crouch, R. David,Mitten, Jeffrey V.,Span, Amelia R.,Dai, H. George
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p. 791 - 794
(2007/10/03)
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