- Synthesis and radiofluorination of iodophenyl esters as tool for the traceless staudinger ligation
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A new synthetic pathway for the preparation of ω-functionalized 2-iodophenyl esters as starting materials for the synthesis of substituted phosphanes is described. A radiolabeling of these esters with fluorine-18 has led to building blocks which were reacted with HPPh2 in a Pd-catalyzed P-C cross coupling to establish new phosphanes. These compounds can be applied as mild and bioorthogonal radiolabeling agents by means of the traceless Staudinger ligation. A route to access this class of compounds has been established.
- Pretze, Marc,Flemming, Anke,Koeckerling, Martin,Mamata, Constantin
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experimental part
p. 1128 - 1136
(2011/01/09)
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- β-lactams from D-erythrose-derived imines: A convenient synthesis of 2,3-diamino-2,3-dideoxy-d-mannonic-acid derivatives
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The D-manno-configured N-anisylated β-lactam 40, the β-lactam carboxylic acids 4 and 43, and the corresponding phosphonic-acid isosters 49 and 50 have been synthesized from D-glucose in 8-10 steps, respectively. None of these compounds exhibited a significant inhibitory activity in vitro against the sialidases of Vibrio cholerae, Salmonella typhimurium, Influenza A (N9), and Influenza B virus. Cycloaddition of the in situ generated imines derived from the D-erythroses 6, 16, and 17 with the ketene from mesyloxyacetyl chloride (20) gave the 2-mesyloxy-D-hexono-1,3-lactams 25, 27a/b, 28a/b/c, and 29 in 23, 69, 57, and 90% yield, respectively (Scheme 3). Transformation of 27a/b and 29 (> 85%) to the corresponding azides, followed by oxidative N-deprotection, gave 30a/b (45%) and 34 (80%). Subsequent alkylation of the ring N-atom in 31a with benzyl bromoacetate and dibenzyl (triflyloxymethyl)phosphonate 46 gave the carboxylate 41 (77%) and the phosphonate 47 (55%; Schemes 4 and 5). Hydrogenolysis of 41 gave the β- lactam amino acid 43, besides its hydrolysis product 44. Reductive N- acylation of the azido group in 41 (93%), followed by hydrogenolytic debenzylation, yielded the 2-trifluoroacetamido N-(carboxymethyl)-β-lactam 4 (56%). Similarly, 47 gave the 2-trifluoroacetamide 48 (89%), and hence, the 2-amino-N-(phosphonoylmethyl)-β-lactams 49 (40%) and 50, resulting from deacylation of 49 (14%). Aminolysis and carbamoylation of the protected β- lactams 31a and 35 led to the 2,3-diamino-2,3-dideoxy-D-mannonamides 51 and 53, respectively (Scheme 6).
- Storz, Thomas,Bernet, Bruno,Vasella, Andrea
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p. 2380 - 2412
(2007/10/03)
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