Synthesis and Antibacterial Activities of (9S)-3-O-descladinose-6-Omethyl- 3-oxo-12-(Δ 2-pyrazolinyl)-12-dehydroxy-21-demethyl-9- dihydroerythromycin A

A new kind of ketolides, bearing a pyrazolinyl moiety at C-12 position, was designed and firstly synthesized starting from clarithromycin via ten steps. The title compound was evaluated for its antibacterial activities against several pathogens in vitro, and was found with potent effects on both S. aureus (ATCC6538p) and S. epidermidis (ATCC12228). The structures of new compounds were elucidated by 1HNMR, 13CNMR, MS and HRMS.