Peptides alkylations, sodium hydride

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)... 

At the beginning, permethylated peptide libraries were derived by a post-modification of peptide libraries attached to the solid-phase support. The amide bond functionalities were alkylated using a solution of sodium hydride in dimethylsulfoxide, followed by addition of neat methyl iodide, therefore generating libraries from libraries . A peptide library that underwent this simple chemical transformation was used to identify compounds with potent antimicrobial activity against Gram-positive bacteria [21]. 

Acyl amino acids and peptides may be alkylated on nitrogen using sodium hydride, with noracemization (eq 9). A slight change of reaction conditions allows simultaneous esterification. ... 

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. 

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