N-DEMETHYL ERYTHROMYCIN A synthesis

Yield: 84%

Reaction Conditions:

with sodium hydroxide;iodine;sodium acetate in methanol;water; pH=8 - 9 at 20 - 50; for 3.5 h;

Steps:

4 Synthesis of 3'-de-N-methyl erythromycin A (EM798)
Synthesis of EM798 is described in L. A. Freiberg and Japanese Patent Kokai Hei 47-9129 A. Sodium acetate (146.4 mg, 1.785 mmol) and iodine (99.6 mg, 0.392 mmol) were added sequentially to the stirred solution of erythromycin A (267.0 mg, 0.375 mmol) in methanol (58.0 mL) and water (12.0 mL) at room temperature. The reaction mixture was stirred at 50 °C for 3.5 hours. During the reaction, 1N aqueous solution of sodium hydroxide was added dropwise to adjust the pH of the solution to 8.0 - 9.0. The reaction mixture was concentrated in vacuo to remove the methanol. The residue was dissolved in saturated brine and extracted with dichloromethane. The extracts were dried over anhydrous sodium sulfate, and distilled off the solvent to obtain the crude product. The resulting crude product was purified by column chromatography on silica gel eluding with chloroform-methanol-aqueous ammonia (10: 0.5: 0.1) to give EM798 (221.0 mg, 84 %, white amorphous solid).

References:

THE KITASATO INSTITUTE EP1559719, 2005, A1 Location in patent:Page/Page column 17