NOVELTY - Synthesizing carbapenem and carbapenem antibiotic key intermediate 4AA comprises carrying out diazotization of L-threonine, sodium nitrite, hydrochloric acid and sodium hydroxide and then performing intramolecular nucleophilic substitution reaction to generate (2R,3R)-3-methyl-oxirane-2-carboxylic acid as a intermediate (I), carrying out nucleophilic substitution reaction of 4-methoxy-phenylamine to generate 1-(dimethyloxidanyl)-2-((4-methoxyphenyl)amino)ethanone as a intermediate (II), and reacting intermediate (I) and (II).    USE - The method is useful for synthesizing carbapenem and carbapenem antibiotic key intermediate 4AA (claimed).    ADVANTAGE - The method produces carbapenem and carbapenem antibiotic key intermediate 4AA with mild reaction condition, short reaction time, low pollution and high yield, and is suitable for industrial production.    DETAILED DESCRIPTION - Synthesizing carbapenem and carbapenem antibiotic key intermediate 4AA, comprises (1) carrying out diazotization of L-threonine, sodium nitrite, hydrochloric acid and sodium hydroxide and then performing intramolecular nucleophilic substitution reaction to generate (2R,3R)-3-methyl-oxirane-2-carboxylic acid as a intermediate (I), (2) carrying out nucleophilic substitution reaction of 4-methoxy-phenylamine to generate 1-(dimethyloxidanyl)-2-((4-methoxyphenyl)amino)ethanone as a intermediate (II), (3) reacting intermediate (I) and (II) to generate N-(2-(dimethyloxidanyl)-2-oxo-ethyl)-N-(4-methoxyphenyl)-3-methyl-oxirane-2-carboxamide as a intermediate (III), (4) performing cyclization reaction of (III) and hexamethyldisilazane in the presence of lithium amide and tetrahydrofuran to generate 4-(dimethyloxidanyl)-2-(1-hydroxyethyl)-N-(4-methoxyphenyl)-3-methyl-4-oxo-butanamide as a intermediate (IV), (5) reacting (IV) and tert-butyldimethylsilyl chloride to generate isopropyl 4-(tert-butyl(dimethyl)silyl)peroxy-3-((4-methoxyphenyl)carbamoyl)-2-methyl-pentanoate as a intermediate (V), (6) carrying out hydrolysis reaction of (V) and sodium hydroxide, hydrochloric acid to generate 4-(tert-butyl(dimethyl)silyl)peroxy-3-((4-methoxyphenyl)carbamoyl)-2-methyl-pentanoic acid as a intermediate (VI), (7) carrying out oxidation and decarboxylation reaction of (VI) to generate (3-(tert-butyl(dimethyl)silyl)peroxy-2-((4-methoxyphenyl)carbamoyl)-1-methyl-butyl) acetate as a intermediate (VII), and (8) performing ozone removing reaction of (VII) to generate 4-AA group of (2-acetyl-3-(tert-butyl(dimethyl)silyl)peroxy-1-methyl-butyl) acetate.