- Svetamycins A-G, Unusual Piperazic Acid-Containing Peptides from Streptomyces sp.
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Seven new halogenated peptides termed svetamycins A-G (1-7) have been isolated from laboratory cultures of a Streptomyces sp. Svetamycins A-D, F, and G are cyclic depsipeptides, whereas svetamycin E is a linear analogue of svetamycin C. Their structures were determined using extensive spectroscopic analysis, and their stereochemical configuration was established by a combination of NMR data, quantum mechanical calculations, and chemical derivatizations. Svetamycins are characterized by the presence of a hydroxyl acetic acid and five amino acids including a rare 4,5-dihydroxy-2,3,4,5-tetrahydropyridazine-3-carboxylic acid, a γ-halogenated piperazic acid, and a novel δ-methylated piperazic acid in svetamycins B-C, E, and G. Moreover, isotope-labeled substrate feeding experiments demonstrated ornithine as the precursor of piperazic acid and that methylation at the δ position of the piperazyl scaffold is S-adenosyl-l-methionine (SAM)-dependent. Svetamycin G, the most potent antimicrobial of this suite of compounds, inhibited the growth of Mycobacterium smegmatis with an MIC80 value of 2 μg/mL.
- Dardi?, Denis,Lauro, Gianluigi,Bifulco, Giuseppe,Laboudie, Patricia,Sakhaii, Peyman,Bauer, Armin,Vilcinskas, Andreas,Hammann, Peter E.,Plaza, Alberto
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p. 6032 - 6043
(2017/06/23)
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- Study on the total synthesis of velbanamine: Chemoselective dioxygenation of alkenes with PIFA via a stop-and-flow strategy
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A "stop-and-flow" strategy was developed for the chemoselective dioxygenation of alkenes with a PIFA-initiated cyclization. This method is conceived for the desymmetrization of seco-diene, and a series of substituted 5-hydroxymethyl-γ-lactones were constructed after hydrolysis. This strategy also differentiates terminally substituted alkenes and constitutes a potentially novel synthetic approach for the efficient synthesis toward velbanamine.
- Liu, Huili,Zheng, Kuan,Lu, Xiang,Wang, Xiaoxia,Hong, Ran
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p. 983 - 990
(2013/07/19)
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- First total synthesis of Debilisone C
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Total synthesis of Debilisone C, a lactone containing conjugated endiyne has been achieved. The adopted strategy involves the stereoselective construction of the five membered lactone ring and the C20 endiyne chain followed by regioselective coupling of both the parts. The lactone was obtained from the oxidative cleavage of the hydroxy olefin which was derived from the benzyl protected S-epichlorohydrine by regioselective epoxide opening with allyl trimethyl silane in presence of a Lewis acid at -78 °C. Takai olefination, Pd0/Ag1 catalyzed cross-coupling reaction and selective substitution of trimethylsilyl groups were successfully utilized to establish the C20 polyyne chain. The final coupling of both the parts have been carried out by alkyl coupling using LDA in THF-DMPU (1 : 1).
- Saikia, Bishwajit,Joymati Devi, Thongam,Barua, Nabin C.
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p. 905 - 913
(2013/03/14)
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- Practical synthesis of C1-8 fragment of autolytimycin via a chelation-controlled diastereoselective addition of diisopropenylzinc to α-methoxy aldehyde
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The C1-8 fragment of autolytimycin was synthesized via a reliable 10-step route capable of delivering 41% overall yield at multi-gram scale. As a key step, a chelation-controlled isopropenylation of α-oxygenated aldehydes was established with a reagent combination of diisopropenylzinc, magnesium halide, and a dichloromethane/toluene mixed solvent. Cram-chelate isopropenylation products dominated for aldehydes with a small α-substituents, such as -OMe and -OBn groups, while the Felkin product could be obtained with a bulky -OTBS group.
- Yang, Fan,Feng, Liang,Wang, Nengzhong,Liu, Xuge,Li, Jun,Shen, Yuehai
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p. 9463 - 9468
(2013/10/08)
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- Pyrene intercalating nucleic acids with a carbon linker
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We have synthesized a carbon linker analogue of INA (oligonucleotides containing insertions of 1-O-(1-pyrenylmethyl)glycerol). Thermal stability studies showed an increase in melting temperature in favor of the carbon linker analogue. We also synthesized a carbon linker analogue with two pyrenes geminally attached. Fluorescence studies of this intercalating nucleic acid with the pyrene moieties inserted as a bulge showed formation of an excimer band. When a mismatch was introduced at the site of the intercalator, an excimer band was formed for the destabilized duplexes whereas an exciplex band was observed when the stability of the duplex was retained. Copyright Taylor and Francis Group, LLC.
- stergaard, Michael E.,Wamberg, Michael C.,Pedersen, Erik B.
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p. 210 - 226
(2012/04/18)
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- Cyclopropenium-activated cyclodehydration of diols
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The dehydrative cyclization of diols to cyclic ethers via cyclopropenium activation is described. Using 2,3-diphenylcyclopropene and methanesulfonic anhydride, a series of 1,4-and 1,5-diols are rapidly cyclized to furnish tetrahydrofurans and tetrahydropyrans in high yield. Eleven total substrates are shown, including a gram scale cyclization of a diterpene derivative.
- Kelly, Brendan D.,Lambert, Tristan H.
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supporting information; experimental part
p. 740 - 743
(2011/05/04)
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- Drug delivery by an enzyme-mediated cyclization of a lipid prodrug with unique bilayer-formation properties
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Special delivery: Liposomal drug-delivery systems in which prodrugs are activated specifically by disease-associated enzymes have great potential for the treatment of severe diseases, such as cancer. A new type of phospholipid-based prodrug has the ability to form stable small unilamellar vesicles (see picture). Activation of the prodrug vesicles by the enzyme sPLA2 initiates a cyclization reaction, which leads to the release of the drug.
- Linderoth, Lars,Peters, Gnther H.,Madsen, Robert,Andresen, Thomas L.
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supporting information; experimental part
p. 1823 - 1826
(2009/09/07)
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- Benzyl N-phenyl-2,2,2-trifluoroacetimidate: A new and stable reagent for O-benzylation
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A new O-benzylation reagent, benzyl N-phenyl-2,2,2-trifluoroacetimidate, has been developed. It even reacts with sterically hindered alcohols and base-sensitive hydroxy esters to afford the corresponding benzyl ethers catalyzed by TMSOTf in 1,4-dioxane. This reagent was more stable than benzyl 2,2,2-trichloroacetimidate, a known benzylation reagent. Copyright
- Okada, Yasunori,Ohtsu, Mamiko,Bando, Masafumi,Yamada, Hidetoshi
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p. 992 - 993
(2008/02/10)
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- Efficient chirality transfer in the Sml2-mediated cyclization of aldehydo β-alkoxyvinyl sulfoxides: Asymmetric synthesis of 3-hydroxyoxanes
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Stereoselective syntheses of 3-hydroxyoxanes were achieved via efficient chirality transfer in the Sml2-mediated cyclization reactions of aldehydo β-alkoxyvinyl sulfoxides.
- Jung, Jae Hoon,Kim, Yong Wook,Kim, Min Ah,Choi, Soo Young,Chung, Young Keun,Kim, Tae-Rae,Shin, Seokmin,Lee, Eun
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p. 3225 - 3228
(2008/02/11)
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- Synthesis of γ- and δ-lactones from alkynols
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The reaction of alkynyl phenyl selenides with p-toluene-sulfonic acid gives rise to a proton-induced ring-closure reaction affording γ- and δ-lactones. Georg Thieme Verlag Stuttgart.
- Tiecco, Marcello,Testaferri, Lorenzo,Temperini, Andrea,Terlizzi, Raffaella,Bagnoli, Luana,Marini, Francesca,Santi, Claudio
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p. 587 - 590
(2007/10/03)
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- Pectenotoxin-2 synthetic studies. 2. Construction and conjoining of ABC and DE eastern hemisphere subtargets
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(Chemical Equation Presented) Practical asymmetric synthesis of aldehyde 2 and tetrazolyl sulfone 3 has allowed for their coupling via Julia olefination to generate 32 as a single product. This substance possesses the entire carbon backbone of the A-E substructure of pectenotoxin-2.
- Bondar, Dmitriy,Liu, Jian,Mueller, Thomas,Paquette, Leo A.
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p. 1813 - 1816
(2007/10/03)
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- Lactams as EP4 prostanoid receptor agonists. 3. Discovery of N-ethylbenzoic acid 2-pyrrolidinones as subtype selective agents
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Two distinct synthetic schemes were applied to access heteroatom-containing α-chain lactams or lactams terminated as aryl acids. The latter lactams were devised using a pharmacophore for EP4 receptor activity. γ-Lactams were characterized for their prostanoid EP receptor affinities and EP 4 activity and found to be selective for the EP2 and EP4 receptors or selective for the EP4 subtype. Benzoic acid 17 displayed enhanced in vivo exposure relative to 3.
- Elworthy, Todd R.,Brill, Emma R.,Chiou, San-San,Chu, Frances,Harris, Jason R.,Hendricks, R. Than,Huang, Jane,Kim, Woongki,Lach, Leang K.,Mirzadegan, Tara,Yee, Calvin,Walker, Keith A. M.
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p. 6124 - 6127
(2007/10/03)
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- 8-Aza-11-deoxy prostaglandin analogues
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This invention relates to compounds which are generally EP4 receptor agonists and which are represented by Formula I: wherein A is a —CH2—CH2—, or —CH═CH—; B is absent, an aryl, or heteroaryl group; R1 is alkyl, alkenyl, alkynyl, cycloalkylalkyl, heterocyclylalkyl, aryl, arylalkyl or heteroaryl, when B is aryl or heteroaryl and R3, R4, R5 and R6 are not simultaneously hydrogen, or R1 is heterocyclylalkyl, aryl, or heteroaryl when B is absent and R3, R4, R5 and R6 are simultaneously hydrogen; and the other substituents are as defined in the specification; or individual isomers, racemic or non-racemic mixtures of isomers, or pharmaceutically acceptable salts or solvates thereof. The invention further relates to pharmaceutical compositions containing such compounds, methods for their use as therapeutic agents, and methods of preparation thereof.
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- Novel chiral glycerol analogues building blocks. Application to the synthesis of bioactive glycoglycerolipid analogues
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Monoacylglycosylglycerols show anti-tumor promoting effects: in order to study the role of the ester function we have prepared by simple methods (R)-1-O-benzyl-1,2-decandiol, (R)-3-O-benzyl-1-O-hexyl-sn-glycerol, and (R)-1-O-benzyl-5-oxo-1,2-decandiol; these optically active compounds are building blocks for the synthesis of monohexanoylglycosylglycerol isosters.
- Ferraboschi,Colombo,Compostella,Reza-Elahi
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p. 1379 - 1382
(2007/10/03)
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- Total synthesis of thyrsiferyl 23-acetate, a specific inhibitor of protein phosphatase 2A and an anti-leukemic inducer of apoptosis
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A convergent synthetic entry to the squalenoid polyether system has been developed and applied to the biologically active marine natural products thyrsiferyl 23-acetate (1a), thyrsiferol (1b), thyrsiferyl 18-acetate (1c), and thyrsiferyl 18,23-diacetate (
- Gonzalez, Isabel C.,Forsyth, Craig J.
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p. 9099 - 9108
(2007/10/03)
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- Novel synthesis of the C1-C15 polyether domain of the thyrsiferol and venustatriol natural products.
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[formula: see text] A convergent construction of the C1-C15 domain of the thyrsiferol-related natural products has been developed. This involved the separate construction of C1-C7 and C8-C15 fragments, their organochromic-mediated coupling, and subsequent
- Gonzalez,Forsyth
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p. 319 - 322
(2008/02/11)
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- A ring closing metathesis-osmylation approach to oxygenated oxepanes as carbohydrate surrogates
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A ring closing metathesis (RCM)-osmylation sequence has been developed for the formation of highly oxygenated cyclic ethers from the corresponding acyclic dienes. A systematic examination of various substrates in this reaction revealed that the process is general in scope and is insensitive to the number of alkoxy substituents present. Subsequent osmylation of the metathesis product proceeds with excellent diastereoselectivity to furnish highly oxygenated oxepanes. These oxepanes represent one-carbon homologated carbohydrates.
- Wong, Jerome C. Y.,Lacombe, Patrick,Sturino, Claudio F.
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p. 8751 - 8754
(2007/10/03)
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- Synthesis of 2'-C-α-methyl-2',3'-dideoxynucleosides
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A general method for the synthesis of 2'-C-α-methyl-2',3'-dideoxynucleosides is presented. Stereofacial selectivity of the 2-C-methylation reaction of γ-lactone has been investigated, in which the presence of a bulky group at the 5-hydroxymethyl produced the α-isomer as a major product. During glycosylation, the α-methyl group directed the formation of nucleosides in favor of the β-isomer. This methodology is applied to the synthesis of some new pyrimidine and purine nucleosides.
- Giri,Bolon,Chu
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p. 183 - 204
(2007/10/03)
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- Enzymatic Synthesis of Optically Active (S)-(+)-2-Hydroxymethyl-3,4-dihydro-2H-pyran and (S)-(+)-2-Acetoxymethyl-3,4-dihydro-2H-pyran
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Porcine pancreas lipase(PPL)-catalyzed acetylation of (+/-)-2-hydroxymethyl-3,4-dihydro-2H-pyran with vinyl acetate in organic solvent afforded (S)-(+)-2-acetoxymethyl-3,4-dihydro-2H-pyran.Alternatively, (+/-)-2-acetoxymethyl-3,4-dihydro-2H-pyran was resolved via hydrolysis catalyzed by PPL in acetone-phosphate buffer system to afford (S)-(+)-2-hydroxymethyl-3,4-dihydro-2H-pyran with high enantiomeric purity.
- Kang, Suk-Ku,Jeon, Jae-Ho,Yamaguchi, Tokutarou,Hong, Ryung-Kee,Ko, Byoung-Seob
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- Total Synthesis of (10ξ,15R,16S,19S,20S,34R)-Corossoline
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(10ξ,15R,16S,19S,20S,34R)-Corossoline, a structural representative of the cytotoxic monotetrahydrofuranyl annonaceous acetogenins, was synthesized from two chiral starting materials--(S)-glutamic acid and (R)-ethyl lactate, and 10-undecenoic acid.
- Yao, Zhu-Jun,Wu, Yu-Lin
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p. 157 - 160
(2007/10/02)
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- A Useful Application of Benzyl Trichloroacetimidate for the Benzylation of Alcohols
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Primary, secondary and tertiary alcohols, which are sensitive under basic or acidic reaction conditions, can be O-benzylated under mild acidic reaction conditions using benzyl 2,2,2-trichloroacetimidate as the benzylation agent.Chiral substrates, which ha
- Eckenberg, Peter,Groth, Ulrich,Huhn, Thomas,Richter, Norbert,Schmeck, Carsten
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p. 1619 - 1624
(2007/10/02)
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- Total synthesis of hemibrevetoxin B and (7aα)-epi-hemibrevetoxin B
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The total synthesis of hemibrevetoxin B(1) and (7aα)-epi-hemibrevetoxin B (2) is described. The synthesis of the epimer (2) was achieved through a convergent approach involving coupling of the carboxylic acid 17 carrying the bicyclic pyran system with the hydroxy compound 31 containing the monocyclic pyran system, thionation of the resulting diester 32 to the dithionoester 33, photolytic closure to the oxepane enol ether 34, and hydroxy ketone cyclization to the dioxepane system 40. The Z-diene system was established using a selenyl-Wittig reaction followed by syn elimination of the selenoxide to the diene. The α-vinyl functionality was installed using the Eschenmoser's salt methodology. The synthesis of hemibrevetoxin B(1) was achieved through a linear approach involving sequential formation of the oxepane rings (65 → 67 → 73) using the method of thionolactone formation followed by nucleophilic addition and regio/stereoselective hydroboration (67 → 68, 75 → 76). Elaboration of the side chains was carried out in a similar fashion as described for the epimer. The stereochemistry of the ring junctures in 1 and 2 and intermediates leading to them was established by X-ray crystallographic analysis carried out on compounds 45 and 54. Biological studies with (7aα)-epi-hemibrevetoxin B (2) revealed no binding for this molecule to the brevetoxin receptors.
- Nicolaou,Reddy, K. Raja,Skokotas, Golfo,Sato, Fuminori,Xiao, Xiao-Yi,Hwang
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p. 3558 - 3575
(2007/10/02)
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- Indonesian medicinal plants. IV. On the constituents of the bark of Fagara rhetza (Rutaceae). (2). Lignan glycosides and two apioglucosides
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Two new lignan glycosides, named hazaleanin A (1) and hazaleanin B (2), and two new apioglucosides, named isopropyl apioglucoside (3) and 4-hydroxyguaiacol apioglucoside (4), were isolated from the bark of Fagara rhetza (Rutaceae), an Indonesian medicinal plant from Flores Island, Indonesia. The chemical structures of 1, 2, 3, and 4 have been elucidated on the basis of chemical and physicochemical evidence, including a chiral synthesis of an aglycone derivative of 1.
- Shibuya,Takeda,Zhang,Tanitame,Tsai,Kitagawa
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p. 2639 - 2646
(2007/10/02)
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- A Convenient Synthesis of (R)-Japonilure
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The title pheromone has been synthesised in high optical purity using easily accessible (S)-glycerol-2,3-acetonide (2) as the starting chiron.
- Chattopadhyay, S.,Mamdapur, V. R.,Chadha, M. S.
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p. 1299 - 1303
(2007/10/02)
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- Efficient Synthesis of (R)-(-)-γ-Benzyloxymethyl-γ-butyrolactone from (D)-(+)-Mannitol
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Efficient synthesis of (R)-(-)-γ-benzyloxymethyl-γ-butyrolactone (10) has been developed using (D)-(+)-mannitol (1) as starting material.
- Takano, Seiichi,Goto, Emiko,Hirama, Michiyasu,Ogasawara, Kunio
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p. 381 - 385
(2007/10/02)
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