Process for the preparation of 9-deoxo-8a-aza-(8a-alkyl)-8a-homoerythromycin A derivatives from 9-deoxo-9 (Z)-hydroxyiminoerythromycin A

摘要

The invention provides a process for the preparation of 9-deoxo-8a-aza-8a-homoerythromycin Aand of its 8a-alkylated derivatives from 9-deoxo-9(Z)-hydroxyiminoerythromycin A via a stereospecific Beckmann rearrangement in a reaction mixture using pyridine as main solvent, resulting in imidate intermediates which are not isolated from said mixture and which are employed directly in a reduction stage using a sufficient amount of borohydride, after extraction of the pyridine with a hydrocarbon which is miscible with the latter and in which said imidates are insoluble. The compound V can be directly N-alkylated at the 8a-position using an aldehyde without being isolated from the reduction mixture.