Preparation method of penem antibiotic intermediate

The invention provides a preparation method of a penem antibiotic intermediate (3R,4R)-4-acetoxyl-3-[(R)-1-tertiary butyl dimethyl silicon oxo-ethyl]-1-methoxyphenyl-2-azacyclobutanone. The penem antibiotic intermediate is prepared by reacting (3R,4R)-4-carboxyl-3-[(R)-1-tertiary butyl dimethyl silicon oxo-ethyl]-1-methoxyphenyl-2-azacyclobutanone with an oxidant in the presence of a catalyst and a cocatalyst, wherein the oxidant is selected from potassium permanganate, sodium bromated, hydrogen peroxide or ammonium persulfate; the catalyst is selected from copper acetate, manganese acetate, ammonium ceric nitrate or manganese dioxide; and the cocatalyst is selected from sodium acetate or potassium acetate. According to the preparation method, the conventional reagents instead of toxic metal or noble metal are involved in the reaction, so the activity and the selectivity are high and the products have high yield and purity; and the reaction time is short and the reaction condition is mild, so the preparation method is suitable for industrialized production.