Synthesis of derivatives of (9S)-9-hydroxyl-12-methylene erythromycin A and their antibacterial activity in vitro

The derivatives of (9S)-9-hydroxyl-12-methylene erythromycin A were synthesized by using erythromycin A as a starting material. An intermediate (9S)-9,11-O-isopropylidene-6-O-allyl-2′,4″-O-bis(benzoyl)-12,21-anhydro erythromycin A 12 was obtained. The antibacterial activity in vitro of two compounds, 6 and 11, was tested. The preliminary biological test showed that two compounds exhibited less potent antibacterial activity in vitro.