Applications of Sugar Nitrones in Synthesis: The Total Synthesis of (+)-Polyoxin J1
摘要:
A convergent synthesis of the peptidyl nucleoside antibiotic (inhibitor of chitin biosynthesis) polyoxin J (2) by coupling of 5-O-carbamoyl polyoxamic acid (3) and thymine polyoxin C (4) is described. These compounds were prepared by chain elongation and amination of sugar-derived aldehydes employing their nitrones as iminium derivatives and the furan ring as a masked carboxyl. Thus, the stereoselective addition of 2-lithiofuran to the L-threose derived N-benzyl nitrone 5 followed by reduction of the resulting hydroxylamine to amine, carbamoylation of the free hydroxy group, and oxidative cleavage of the furan ring to the carboxylate group gave a protected derivative of 3 (30%). The same method was followed for the synthesis of the ribofuranosyl alpha-amino acid nucleoside 4 (12.6%) starting from the D-ribose derived nitrone 6. The final coupling was performed by the N-hydroxysuccinimide active ester method in DMSO with the Hunig base (i-Pr2EtNH) using a derivative of 3 and unprotected 4.
Dondoni, Alessandro; Franco, Santiago; Junquera, Federico, Chemistry - A European Journal, 1995, vol. 1, # 8, p. 505 - 520
作者:Dondoni, Alessandro、Franco, Santiago、Junquera, Federico、Merchan, Francisco L.、Merino, Pedro、et al.
DOI:——
日期:——
Synthesis of N-Benzyl Nitrones
作者:A. Dondoni、S. Franco、F. Junquera、F. L. Merchán、P. Merino、T. Tejero
DOI:10.1080/00397919408010565
日期:1994.10
A general procedure for the synthesis of twenty-seven chiral and achiral N-benzyl nitrones 1 is described.
Stereoselective Addition of 2-Furyllithium and 2-Thiazolyllithium to Sugar Nitrones. Synthesis of Carbon-Linked Glycoglycines
作者:Alessandro Dondoni、Federico Junquera、Francisco Luis Merchán、Pedro Merino、Marie-Christine Scherrmann、Tomas Tejero
DOI:10.1021/jo970290a
日期:1997.8.1
A route to epimeric carbon-linked glycoglycines that exploits the stereoselective addition of 2-lithiofuran and 2-lithiothiazole to sugar nitrones has been described. The reaction occurs with opposite diastereofacial selectivity depending on whether the free nitrone or the diethyl aluminum chloride precomplexed derivative is employed. The resulting furyl or thiazolyl hydroxylamines are dehydroxylated to amines by the action of titanium(III) chloride. From these compounds the amino acids are revealed by the oxidative cleavage of the furan ring or by the conversion of the thiazole into the formyl group and oxidation to carboxylic acid. Compounds have been prepared wherein the alpha-amino acid moiety is installed at C-4 and C-1 of furanoses (ribo, manno, xylo, and lyxo) and at C-5 and C-1 of a pyranose (galacto).
Porphyrins in 1,3-dipolar cycloaddition reactions with sugar nitrones. Synthesis of glycoconjugated isoxazolidine-fused chlorins and bacteriochlorins
Glycoconjugated isoxazolidine-fused chlorins and bacteriochlorins were prepared in moderate to good yields by 1,3-dipolar cycloaddition reactions of meso-tetrakis(pentafluorophenyl)porphyrin with glycosyl nitrones. (C) 2002 Elsevier Science Ltd. All rights reserved.