Metal catalyzed diazo transfer for the synthesis of azides from amines

Alper, Phil B.; Hung, Shang‐Cheng; Wong, Chi‐Huey

doi:10.1016/0040-4039(96)01307-x

Cited by 338 publications

(236 citation statements)

References 8 publications

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“…The assignment of the stereogenic centers of the DAP dimethylesters was accomplished by conversion of each single diastereomer to the bis-Ncamphanic acid amide derivative and NMR analysis (600 MHz) of the methyl ester region (25). The muramic acid moiety (Table II, b) was synthesized according to our previously published method (26,27) from 1,3,4,6-tetra-O-acetyl-2-azido-2-deoxyglucopyranose (28). Saponification of the methyl ester of two and attachment of the first amino acid (L-alanine methyl ester) prevented the often observed formation of muramic acid 1Ј,2-lactam during azide reduction (29,30).…”

Section: Methodsmentioning

confidence: 99%

Structural Requirements of Synthetic Muropeptides to Synergize with Lipopolysaccharide in Cytokine Induction

Traub

Kubasch

Morath

et al. 2004

Journal of Biological Chemistry

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Muropeptides contribute to the recognition of bacteria by modulating immune responses: the structural requirements for adjuvant activity were described in the seventies. During the last years, our knowledge of bacterial pattern recognition has increased dramatically and the importance of the absence of contaminations in both muropeptide preparations and other bacterial stimuli has become clear. We investigated a panel of 15 synthetic Limulus-negative muropeptides, four of them synthesized for the first time, as to their potency to synergize with lipopolysaccharide (LPS) in cytokine induction in human whole blood. No muropeptide was capable of stimulating cytokine release from human blood. However, as little as 20 nM of the muropeptides N-acetyl-muramyl-L-alanyl-D-isoglutamine (muramyl dipeptide, M(ADiQ)), N-acetyl-glucosamine-muramyl dipeptide GM(ADiQ), or C 18 M(ADiQ), which carries a non-natural additional fatty acid, sufficed to induce an up to 3 log-order shift in tumor necrosis factor ␣-release in response to 100 pg/ml LPS. The release of interleukin-1␤, interleukin-6, and interleukin-10 was also significantly enhanced although to a lesser extent. The synergistic effect was stereoselective with M(ADiQ) being the minimal active principle. Synergy was also observed on the transcriptional level by means of real-time PCR. Smaller molecules like N-acetylmuramic acid (M), AM, carrying a naturally occurring 1,6-anhydro-bound in M or M(A), containing only the amino acid L-alanine neither synergized with LPS nor influenced the synergy of other muropeptides with LPS. In conclusion, these data show that nanomolar quantities of muropeptides dramatically potentiate LPS-induced monocyte activation. This has implications for pyrogenicity testing and endotoxemia in patients.

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Section: Methodsmentioning

confidence: 99%

Structural Requirements of Synthetic Muropeptides to Synergize with Lipopolysaccharide in Cytokine Induction

Traub

Kubasch

Morath

et al. 2004

Journal of Biological Chemistry

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“…The amino group of 11 was masked as azide by trifluoromethanesulfonyl azide; the configuration of the stereo center of the amino group was retained under the condition. 44 The primary hydroxyl group of 12 was selectively converted to the nosylate, and then to the cyclohexylamino group by nucleophilic displacement. The resulting intermediate, 14, was elaborated to the final compound, 17, by following the sequence of benzoylation, azide reduction, and ureation.…”

Section: Fas-te Binding Tool Compoundmentioning

confidence: 99%

In vivo Incorporation of Unnatural Amino Acids to Probe Structure, Dynamics, and Ligand Binding in a Large Protein by Nuclear Magnetic Resonance Spectroscopy

et al. 2008

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In vivo incorporation of isotopically labeled unnatural amino acids into large proteins drastically reduces the complexity of nuclear magnetic resonance (NMR) spectra. Incorporation is accomplished by co-expressing an orthogonal tRNA/aminoacyl-tRNA synthetase pair specific for the unnatural amino acid added to the media and the protein of interest with a TAG amber codon at the desired incorporation site. To demonstrate the utility of this approach for NMR studies, 2-amino-3-(4-(trifluoromethoxy) phenyl) propanoic acid (OCF 3 Phe), 13 C/ 15 N-labeled p-methoxyphenylalanine (OMePhe), and 15 N-labeled o-nitrobenzyl-tyrosine (oNBTyr) were incorporated individually into 11 positions around the active site of the 33 kDa thioesterase domain of human fatty acid synthase (FAS-TE). In the process, a novel tRNA synthetase was evolved for OCF 3 Phe. Incorporation efficiencies and FAS-TE yields were improved by including an inducible copy of the respective aminoacyl-tRNA synthetase gene on each incorporation plasmid. Using only between 8 and 25 mg of unnatural amino acid, typically 2 mg of FAS-TE, sufficient for one 0.1 mM NMR sample, were produced from 50 mL of E. coli culture grown in rich media. Singly labeled protein samples were then used to study the binding of a tool compound. Chemical shift changes in 1 H-15 N, 1 H-13 C HSQC and 19 F NMR spectra of the different single site mutants consistently identified the binding site and the effect of ligand binding on conformational exchange of some of the residues. OMePhe or OCF 3 Phe mutants of an active site tyrosine inhibited binding; incorporating 15 N-Tyr at this site through UV-cleavage of the nitrobenzyl-photocage from oNBTyr re-established binding. These data suggest not only robust methods for using unnatural amino acids to study large proteins by NMR but also establish a new avenue for the site-specific labeling of proteins at individual residues without altering the protein sequence, a feat that can currently not be accomplished with any other method.

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“…The product, recovered as colorless oil, crystallized to a white waxy solid. Spectral data were identical as previously reported [24] …”

Section: 5-anhydro-3-o-benzyl-2-deoxy-d-arabino-hex-1-enitol (4)mentioning

confidence: 75%

“…The N-acetyl functionality of compound 16 was removed by heating with aqueous Ba(OH) 2 [23] to yield the amino sugar 17 after neutralization with aqueous sulfuric acid (1N). Treatment of 17 with triflic azide and CuSO 4 in MeOH [24] produced the azido sugar 18 in 74 % yield. The OH-3 functional group of compound 18 was protected as the benzyl ether, by reaction with benzyl bromide and sodium hydride in DMF yielding compound 19 (86 %) and as the levulinoyl ester, by reaction of 18 with a mixture of levulinic acid, DCC, and DMAP in CH 2 Cl 2 to produce compound 20 (73 %).…”

Section: Resultsmentioning

confidence: 99%

Preparation of a set of selectively protected disaccharides for modular synthesis of heparan sulfate fragments: toward the synthesis of several O-sulfonated [β-D-GlcUA-(1→4)-β-D-GlcNAc]OPr types

Hassan

2005

Open Chemistry

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A concise method for a stereocontrolled synthesis of a set of selectively protected disaccharides is reported. Coupling of the donor 11 onto acceptors 23 and 24, promoted by trimethylsilyl triflate-N-iodosuccinimide (TMSOTf-NIS), generated the disaccharides 25 and 26. Under typical conditions, condensation of the fully protected donor 12 onto acceptors 23 and 24 produced the disaccharides 27 and 28. The building blocks 25–28 were prepared in moderate yields having exclusive β-stereoselectivity. A unique pattern of protecting groups distinguished clearly between positions to be sulfated and functional groups remaining as free hydroxyl groups. Acetyl and/or levulinoyl esters temporarily protected the positions to be sulfated, while benzyl ethers were used for permanent protection. The anomeric positions were protected as allyl ethers, whereas the 4′-positions were masked as p-methoxybenzyl (PMB) ethers. The orthogonality of the PMB and allyl groups can then be used for further elongation of the chain by recurrent deprotection and activation steps. The hydroxyl group, OH-6, of glucosamine moieties was protected as a TBDPS ether to avoid oxidation. A five-step deprotection/sulfonation sequence was applied to the disaccharide 27 to generate the corresponding sulfated [β-D-GlcUA-2-OSO3Na-(1→4)-β-D-Glc pNAc]-(1→O-Pro) 34.

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Metal catalyzed diazo transfer for the synthesis of azides from amines

Cited by 338 publications

References 8 publications

Structural Requirements of Synthetic Muropeptides to Synergize with Lipopolysaccharide in Cytokine Induction

Structural Requirements of Synthetic Muropeptides to Synergize with Lipopolysaccharide in Cytokine Induction

In vivo Incorporation of Unnatural Amino Acids to Probe Structure, Dynamics, and Ligand Binding in a Large Protein by Nuclear Magnetic Resonance Spectroscopy

Preparation of a set of selectively protected disaccharides for modular synthesis of heparan sulfate fragments: toward the synthesis of several O-sulfonated [β-D-GlcUA-(1→4)-β-D-GlcNAc]OPr types

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