Identification of an Impurity in Synthetically Prepared GAZT: 4′′,5′′- Dehydro-GAZT

A minor impurity was recorded by hplc during the final purification of synthetically prepared samples of the 5'-O-glucuronide of azidothymidine (GAZT). Following isolation of a small quantity of this impurity by hplc, elucidation of the structure was undertaken. A combination of two-dimensional nmr methods in conjunction with infrared spectroscopy and mass spectrometry were utilized to unequivocally identify the impurity as the 4",5"-dehydro-5'-O-glucuronide of AZT (DGAZT).