A Novel Glycopeptide Carrying a 3-Oxazolin-5-one Ring Obtained by Intra-molecular Cyclization

The structure of a product, isolated during the synthesis of the semisynthetic glycopeptide MDL 63, 246, was elucidated on the basis of spectroscopic methods and proved to be a novel glycopeptide containing a 3-oxazolin-5-one ring between positions 36 and 38. Subjected to acid hydrolysis this compound gave the corresponding pseudo aglycone and aglycone derivatives which maintained the original oxazolinone structure. Tested for antibacterial activity, these compounds showed a moderate activity against Gram-positive and inactive against Gram-negative bacteria.