Method for preparing 6-O-methyl-2'-O, N-bis (benzyloxycarbonyl) -N-demethylerythromycin A

摘要

PURPOSE:To produce the titled compound useful as an intermediate of an antimicrobial agent effective to Gram-positive and Gram-negative bacteria, mycoplasma, etc., economically in an industrial scale, by selectively O-methylating the tert-OH at the 6-position of an erythromycin A derivative using KOH or NaOH. CONSTITUTION:The objective compound can be produced by carrying out the O-methylation of (A) 2'-O,N-bis(benzyloxycarbonyl)-N-demethylerythromycin A with (B) preferably 1-8 times mole equivalent of a methylation agent (preferably methyl iodide) in (C) an aprotic polar solvent (preferably dimethyl sulfoxide or its mixture with 1,2-dimethoxyethane at a ratio of 1:1-2) in the presence of KOH or NaOH.