SINGLE-STEP PROCESS FOR PREPARING 7,16-DEOXY-2-AZA-10-O-CLADINOSIL-12-O-DESOSAMINIL-4,5-DIHYDROXI-6-ETHYL-3,5,9,11,13,15-HEXAMETHYLBICYCLE (11.2.1)HEXADECA-1(2)-EN-8-ONA AND OBTAINING A NEW FORM OF 9-DESOXO-9A-METHYL-9A-AZA-9A-HOMOERYTHROMYCIN A

摘要

The invention relates to an improved method for preparing 7,16-deoxy-2-aza-10-O-cladinosil-12-O-desosaminil-4,5-dihydroxi-6-ethyl-3,5,9,11,13,15-hexamethylbicycle[11.2.1]hexa-deca-1(2)-en-8-ona from erythromycin A, wherein said compound is obtained from erythromycin A with high yields and under soft and adequate production conditions in a single-step process. Transformation of erythromycin A into an intermediate compound called 6,9-iminoether, which is obtained in a single step, is carried out by forming 'in situ' mesitylenesulfonyloxime from erythromycin, which undergoes Beckmann's transposition in the presence of a base in aqueous acetone thus giving rise to the iminoether with the aid of the hydroxyl in position 6 of the macrolide ring. Said intermediate compound is transformed into the antibiotic called 9-deoxo-9a-aza-9a-methyl-9a-homoerythromycin A, which is obtained by appropriate precipitation in hexane. A novel form with an anhydrous crystalline structure and physical properties differing from those of forms known to date is thus obtained.