合成路线1

The condensation of N-(tert-butyldimethylsilyl)-4-oxoazetidine-2(S)-carboxylic acid (I) with 1-chloro-3-iodopropane (II) by means of BuLi and triisopropylamine (TIA) in THF, followed by treatment with HCl, gives the 3(R)-(3-chloropropyl) derivative (III), which is treated with tetrabutylammonium azide and tetrabutylammonium iodide in DMF to yield the 3-azidopropyl derivative (IV). The reduction of (IV) with H2 over Pd/C in DMF affords the 3-aminopropyl compound (V), which is treated with 1-[N,N'-bis(benzyloxycarbonyl)-1H-pyrazole] (VI) in the same solvent to provide the protected 3-guanidinopropyl compound (VII). The esterification of (VII) with NaHCO3, tetrabutylammonium iodide and Bn-Br in DMF gives the benzyl ester (VIII), which is condensed with N-tert-butylpiperazine-1-carboxamide (IX) and phosgene by means of TEA in toluene to yield the protected precursor (X). Finally, this compound is debenzylated by hydrogenation with H2 over Pd/C in dioxane to give the target azetidine-carboxylic acid.