合成路线1

This compound has been obtained by two related ways: 1) The hydrolysis of 4'-(bromomethyl)biphenyl-2-carbonitrile (I) with NaOAc in refluxing acetic acid gives the corresponding carbinol (II), which is oxidized with oxalyl chloride in DMSO/dichloromethane yielding the aldehyde (III). The reductocondensation of (III) with L-valine methyl ester (IV) by means of NaBH4CN in THF affords the N-alkylated valine (V), which is acylated with pentanoyl chloride (VI) and TEA in dichloromethane providing the pentanamide (VII). The reaction of the CN group of (VII) with tributyltin azide in refluxing xylene gives the tetrazol derivative (VIII). Finally, the ester group of (VIII) is hydrolyzed with NaOH to furnish the target compound. 2) L-valine methyl ester (IV) can be condensed directly with the bromo-methyl derivative (I) by means of DIEA in dichloromethane giving the N-alkylated valine (V) already reported.