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The development of rapid radiolabeling techniques under mild reaction conditions involving the short-lived positron emitter fluorine-18 remains a special challenge in organic PET chemistry. This work describes a novel and facile application of the traceless Staudinger ligation as a mild and versatile labeling method for preparation of various radiotracers labeled with fluorine-18. 相似文献
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Constantin Mamat Markus FrankeTim Peppel Martin KöckerlingJörg Steinbach 《Tetrahedron》2011,67(25):4521-4529
An elegant and efficient synthesis approach for the preparation of novel benzoate and nicotinate containing phosphanes is presented. This reaction path has a broad substrate scope. Thus, various functionalized phosphanes were obtained in high yields using an esterification procedure under Steglich conditions. A facile blocking of the phosphorus atom with BH3 was carried out. BH3 as easily insertable and removable protecting group enables a further derivatization of the benzoate residue. The prepared phosphane derivatives proved to be valuable labeling building blocks for the implementation of a bioorthogonal (radio-)fluorination strategy and were applied for labeling purposes using the traceless Staudinger ligation. For this purpose, a selection of azide-functionalized small organic and bioactive sample molecules was prepared. Furthermore, a mild and selective (radio-)fluorination of these derivatives is demonstrated adopting this bioorthogonal ligation method. 相似文献
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Remco MerkxDirk T.S. Rijkers Johan KemminkRob M.J. Liskamp 《Tetrahedron letters》2003,44(24):4515-4518
Here we report the first Staudinger ligations which yield tetra- and pentapeptides starting from N-terminal α-azido peptides and C-terminal peptideo-(diphenylphosphine)phenyl esters. Mass spectrometric analysis of the reaction mixture provided a better insight into the mechanism of the Staudinger ligation and has been used to explain the observed intermediates and to optimize the ligation reaction. As a result, the optimized reaction enables the chemoselective coupling of peptides containing amino acids other than glycine at the ligation site. 相似文献
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Concise and efficient enantioselective total syntheses of heliannuols B and D have been accomplished using chirality transfer through a Lewis acid-promoted Claisen rearrangement for the construction of the C7 tertiary stereogenic center and a relay ring-closing metathesis for assembling the dihydrobenzo[b]oxepine backbone of the natural products as the key steps. 相似文献
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TNFR1-associated death domain protein(TRADD) with arginine N-GlcNAcylation is a novel and structurally unique posttranslational modification(PTM) glycoprotein that blocks the formation of death-inducing signaling complex(DISC),orchestrating host nuclear factor κB(NF-κB) signaling in entero-pathogenic Escherichia coli(EPEC)-infected cells.This particular glycosylated modification plays an extremely vital role for the effective colonization and pathogenesis of pathogens in the gut.Herein we descri... 相似文献
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Total syntheses of the microtubule stabilizing antitumor drugs epothilone B and D are described, starting from optically pure (S)-malic acid and methyl (R)-3-hydroxy-2-methylpropionate. The synthesis is highly convergent by coupling the three fragments C1-C6 (fragment D), C7-C10 (fragment C), and C11-C21 (fragment B). Key steps are two stereoselective Wittig type olefinations to generate the 12,13- and 16,17-double bonds, an enantioselective Mukaiyama aldol addition to synthesize fragment D, and a sulfone anion allyl iodide alkylation to connect fragments B and C. Finally fragment D was attached to the B + C fragment via aldol addition. 相似文献
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Vinylketenes possessing a γ-heteroatom, on Staudinger cycloaddition reaction with imines gave trans-3-vinyl-β-lactams in very good yields. The vinyl side chain stereoselectively adopts the Z-configuration in the transition state to stabilize the vinylketene and produces, exclusively, trans-3-vinyl-β-lactams. 相似文献
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Kai-Qing Ma Yan-Hong Miao Xiao-Xia Gao Jian-Bin Chao Xiang Zhang Xue-Mei Qin 《中国化学快报》2017,28(5):1035-1038
An efficient route to the natural products bupleurynol and its analog (RB-2), isolated from Bupleuri Radix, was established based on versatile intermediate (15). In this synthetic route, Sonogashira and Cadiot-Chodkiewicz coupling as well as Julia-Kocienski olefination are utilized as key steps. The highly efficient synthetic route provides opportunities to explore the biological behavior of bupleurynol and RB-2. 相似文献
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The efficient total syntheses of Nigrasin I and Kuwanon C, two biologically interesting natural flavonoids with two regioisomeric isoprenyl side chains, were realized for the first time starting from commercially available 1-(2,4,6-trihydroxyphenyl)ethanone via a linear reaction sequence of 11 steps with the overall yields of 22% and 21%, respectively, in which the selection of protective groups and the Claisen rearrangement of the allylated 16 featured the synthetic strategy. The use of acetic anhydride as the solvent and the employment of microwave irradiation are disclosed to be critically important in the efficient and selective Claisen rearrangement. 相似文献
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Andrew D. Kosal Erin E. Wilson Prof. Dr. Brandon L. Ashfeld 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(45):14444-14453
A chlorophosphite‐modified, Staudinger‐like acylation of azides involving a highly chemoselective, direct nucleophilic acyl substitution of carboxylic acids is described. The reaction provides the corresponding amides with analytical purity in 32–97 % yield after a simple aqueous workup without the need for a pre‐activation step. The use of chlorophosphites as dual carboxylic acid–azide activating agents enables the formation of acyl C? N bonds in the presence of a wide range of nucleophilic and electrophilic functional groups, including amines, alcohols, amides, aldehydes, and ketones. The coupling of carboxylic acids and azides for the formation of alkyl amides, sulfonyl amides, lactams, and dipeptides is described. 相似文献
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Two proposed structures of cuevaene A were synthesized and the NMR spectra of both structures are proved to be inconsistent with those of the natural product. The structure of cuevaene A is still unclear and needs to be revised. 相似文献
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Kishore Kumar Anantoju Thirumala Chary Maringanti Baquer Syed Mohd. 《Tetrahedron letters》2018,59(30):2938-2940
Total synthesis of modified pentapeptide, caldoramide, a cytotoxic linear pentapeptide from the marine cyanobacterium Caldora penicillate is described. Notable features of the route include the efficient preparation of three key fragments and final assembly to the natural product via sequential amide couplings. The spectral data of the synthetic compound was found to be in comparison with that of the isolated natural product. 相似文献
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Concise total syntheses of dehydrobotrydienal, dehydrobotrydienol, and 10-oxodehydrodihydrobotrydial were accomplished via tandem Pauson–Khand and 6π-electrocyclization reactions. 相似文献
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Luiz Fernando Toneto Novaes Roberta Lopes DrekenerCarolina Martins Avila Ronaldo Aloise Pilli 《Tetrahedron》2014
The first total synthesis and structural elucidation of cryptomoscatone D1, and a novel synthetic approach for cryptomoscatone D2 were achieved in 30% and 29% overall yield, respectively. The synthesis relied on the use of a key Mukaiyama aldol reaction followed by a diastereoselective carbonyl reduction that allowed the preparation of four cryptomoscatone isomers in a stereochemically divergent manner. Comparison of NMR data and CD curves of the synthetic stereoisomers and natural products confirmed the stereochemical nature of cryptomoscatone D2, and led to establishing the absolute configuration of cryptomoscatone D1. 相似文献
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Akari MiyawakiMayu Osaka Makoto KanematsuMasahiro Yoshida Kozo Shishido 《Tetrahedron》2011,67(35):6753-6761
The enantioselective syntheses of the compounds with the assigned structures of the helibisabonols A and B have been accomplished. Using an enzymatic desymmetrization of the σ-symmetrical diol (route a) and a diastereoselective conjugate addition of the methyl to the enone with a chiral auxiliary (route b) we constructed the key tertiary stereogenic center at the benzylic position (C7) and then used an asymmetric dihydroxylation for assembling the C10 stereogenic center. In addition, possible diastereoisomers of the natural products were prepared and detailed comparisons of the 1H and 13C NMR spectra were conducted. As a result, the structure originally assigned to helibisabonol A may be revised to (7R,10R)-1. In the case of helibisabonol B, the (7R,10R)-2 would be reasonable based on a comparison of the NMR data and the biogenetic parallelism with helibisabonol A. 相似文献