合成路线1

trans-4-Hydroxy-L-proline (I) was esterified with methanolic HCl, generated from acetyl chloride in MeOH, and the resulting 4-hydroxyproline methyl ester (II) was protected with allyl chloroformate to afford the allyl carbamate (III). Mesylation of the hydroxyl group of (III) with methanesulfonyl chloride, followed by reduction of the methyl ester with LiBH4, provided the alcohol (V). The mesylate group of (V) was then displaced by potassium thioacetate yielding thioacetate ester (VI). Iodo compound (VII) was obtained by mesylation of alcohol (VI) followed by substitution with NaI in acetone. 1-Methyl-5-mercaptotetrazole (IX), prepared by reaction of methyl isothiocyanate (VIII) with NaN3, was then condensed with iodide (VII) to give adduct (X). After deacetylation of thioacetate (X) with methanolic NaOH, the resulting pyrrolidinethiol (XI) was coupled with enol phosphate (XII) to give the protected carbapenem (XIII). The allyl ester and carbamate protecting groups of (XIII) were finally removed by treatment with Bu3SnH in the presence of palladium catalyst.