合成路线1

The selective monoesterification of 2,2-dimethylsuccinic acid (VIII) with methanol and sulfuric acid gives 2,2-dimethylsuccinic acid 4-methyl ester (IX), which is submitted to degradation with diphenylphosphoryl azide, TEA and benzyl alcohol in refluxing benzene, yielding 3-(benzyloxycarbonylamino)-3-methylbutyric acid methyl ester (X). The hydrolysis of (X) with NaOH in methanol affords the corresponding butyric acid (XI). The hydrogenation of 3-azido-2,3,4,5-tetrahydro-1H-1-benzazepin-2-one (XII) with H2 over Pt/C in methanol gives the racemic 3-amino derivative (XIII), which is submitted to optical resolution by crystallization of the L-tartrate salt, yielding the 3(R)-amino derivative (XIV). The condensation of amine (XIV) with acid (XI) by means of benzotriazol-1-yloxytris(dimethylamino)phosphonium hexafluorophosphate (BTPF) and DIEA in dichloromethane affords the corresponding amide (XV), which is condensed with the tetrazole derivative (VII) by means of NaH in DMF to provide the protected adduct (XVI). Finally, this compound is deprotected by hydrogenation with H2 over Pd/C in methanol and a treatment with TFA.