Lipopolysaccharides, alkylation

Blagbrough, I.S., Geall, A.J. and David, S.A. (2000) Lipopolyamines incorporating the tetraamine spermine, bound to an alkyl chain, sequester bacterial lipopolysaccharide. Bioorg. Med. Chem. Lett., 10, 1959-1962. 

Alkyl halide, sodium hydride in DMSO 2.5.1 General, substances insoluble in common organic solvents, polysaccharides, lipopolysaccharides, peptides, sterically hindered functions, amides, amino acids Esters, and as stated for procedure 2.4 peptides containing sulfur-amino acids, histidine and arginine 132] O-Acyl groups are replaced with O-alkyl groups. For N-isopropyl amino acids, isopropyl ester formation, (see Chapter 2)... 

Note The important difference between the alkylation procedures involving sodium hydride in polar apiotic solvents and those involving alkyl halides and metal salts is that 0-acyl groups are completely replaced by 0-alkyl groups [30], N-Acyl groups survive and N-ulkyl-N-acylamido derivatives are produced. This alkylation can be performed on an extremely small amount of material and, thus, the procedure provides a rapid means for methylation linkage analysis in the polysaccharide [30], lipopolysaccharide [31] and peptide [20, 32] fields. 

Alkylation of metal chelates of sucrose with allyl halides and sodium bromo-acetate in DMSO yielded mono-O-allylated and mono-O-carboxymethylated derivatives. A new acidic monosaccharide from the O-specific lipopolysaccharide of Shigella dysenteriae type 3 has been identified as 4-0-[(/ )-l-carboxy-ethyl]-D-glucopyranose on the basis of chemical and mass-spectral evidence and by its synthesis by alkylation of methyl 2,3,6-tri-0-benzyl-a(P)-D-glucopyranoside with (5)-2-chloropropionic acid, esterification (with diazomethane), hydrogenolysis, and acid hydrolysis. ... 

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