Synthesis of α-Cyclooctyl- and α-Cyclopentadecylglycosides of N-Acetylmuramyl-L-Alanyl-D-Isoglutamine

N-Acetylmuramyl-L-alanyl-D-isoglutamine α-cyclooctyl- and α-cyclopentadecylglycosides were synthesized. The starting peracetylated α-N-glucosaminides were synthesized by reacting the cycloalkanols with peracetyl α-D-glucosaminyl chloride in the presence of Hg(II) iodide in CH3NO2 with heating or by using ZnCl2/tetrabutylammonium bromide in CH2Cl2 at room temperature. Sequential deacetylation, isopropyl protection, and alkylation by (S)-2-bromopropanoic acid gave α-cycloalkyl-4,6-O-isopropylidene-N-acetyl-D-muramic acids, condensation of which with the benzyl ester of L-Ala-D-iGln using the HOSu/DCC method and deprotection afforded the target glycopeptides.