Ionic Liquids: New Targets and Media for α-Amino Acid and Peptide Chemistry

The chemistry of α-amino acids and their simple derivatives such as amino alcohols, amino esters, N-protected amino acids, and small peptides in relation to ionic liquids (IL), is studied. Various alkyl amino acid ester salts from the hydrochloride parents are prepared and found to have melting points lower than 105°C. The solubility and miscibility of the ILs depend on the side chain of the amino acids, and all of them are immiscible with ether and miscible with methanol and acetonitrile. Alkylation of imidazole groups provide a chiral bufunctional imidazolium salt whose anion can be subsequently exchanged if needed to adjust the physical and structural properties of salt. Reaction between the protected amino acid and tBu-aniline results in amide, which after deprotection and reduction cycle gives the corresponding diamine.