Clarithromycin was hydrolyzed in different conditions to form 3-hydroxyclarithromycin (2) and 3-hydroxy-8,9,10,11-dehydrous-9,12-hemiketal clarithromycin (3) respectively, then C(2’)-OH of 2 was protected with an acetyl group to yield 2’-acetyl-3-hydroxyclarithromycin (4), C(3)-OH of 4 was then oxi-dized by N-chlorosuccinimide (NCS) to yield 2’-acetyl-3-oxo-clarithromycin (5), and their structures were characterized by MS, IR, 1H NMR and 13C NMR techniques. The crystal structures of 2 and 5 were deter-mined by X-ray single crystal diffraction analysis, which belong to orthorhombic system with space group P212121 and a＝13.657(3) nm, b＝14.783(3) nm, c＝16.510(3) nm, Z＝4, V＝3333.2(12) nm3, Dc＝1.175 g/cm3, F(000)＝1288, μ＝0.087 mm－1 (compound 2); a＝15.124(3) nm, b＝15.247(3) nm, c＝15.288(3) nm, Z＝4, V＝3525.4(12) nm3, Dc＝1.187 g/cm3, F(000)＝1368.0, and μ＝0.088 mm－1 (compound 5).

Key words: clarithromycin, synthesis, crystal structure