合成路线1

The reaction of cyclopentanone (I) with sodium cyanide, NH3 and NH4Cl in hot methanol/water gives 1-aminocyclopentanecarbonitrile (II), which is partially hydrolyzed with concentrated H2SO4 to the corresponding amide (III). The acylation of (III) with pentanoyl chloride (IV) by means of triethylamine in THF yields 1-(pentanamido)cyclopentane-1-carboxamide (V), which, without isolation, is cyclized by means of KOH in refluxing methanol/water to afford 2-butyl-1,3-diazaspiro[4.4]non-1-en-4-one (VI). This compound (VI) can also be obtained by cyclization of 1-aminocyclopentanecarboxylic acid ethyl ester (VII) with pentanimidic ethyl ester (VIII) by means of acetic acid in refluxing xylene. The condensation of (VI) with 4'-(bromomethyl)biphenyl-2-carbonitrile (IX) by means of NaH in DMF gives 4'-(2-butyl-4-oxo-1,3-diazaspiro[4.4]non-1-en-3-ylmethyl)biphenyl-2-carbonitrile (X). Cyclization of (X) with tributyltin azide in refluxing xylene, followed by reaction with trityl chloride in DMF, affords 2-butyl-3-[2'-[1-(triphenylmethyl)tetrazol-5-yl]biphenyl-4-ylmethyl]-1,3-diazaspiro[4.4]non-1-en-4-one (XI). Finally, this compound is hydrolyzed to irbesartan with HCl in methanol/THF. The final cyclization of (X) with tributyltin azide or sodium azide also directly gives irbesartan.

合成路线2

This compound can be obtained by two related ways: 1) The partial esterification of 3-nitrophthalic acid (I) with ethanol and H2SO4 gives 3-nitrophthalic acid 1-monoethyl ester (II), which is treated with SOCl2 in refluxing benzene to yield the corresponding acyl chloride (III). The reaction of (III) first with sodium azide in DMF and then with refluxing tert-butanol affords 2-(tert-butoxycarbonylamino)-3-nitrobenzoic acid ethyl ester (IV), which is condensed with 4-(2-cyanophenyl)benzyl bromide (V) by means of NaH in THF giving 2-(2'-cyanobiphenyl-4-ylmethylamino)-3-nitrobenzoic acid ethyl ester (VI). The reduction of (VI) with SnCl2.2H2O in ethanol yields the corresponding 3-amino derivative (VII), which is cyclocondensed with ethyl orthocarbonate and acetic acid affording 1-(2'-cyanobiphenyl-4-ylmethyl)-2-ethoxybenzimidazole-7-carboxylic acid ethyl ester (VIII). The reaction of (VIII) with trimethyltin azide in refluxing toluene gives the 2'-(1H-tetrazol-5-yl) derivative (IX), which is saponified with NaOH in ethanol to the corresponding free acid (X). Protection of (X) with trityl chloride and triethylamine in dichloromethane gives the protected compound (XI), which is finally esterified with cyclohexyl 1-iodoethyl carbonate (XII) by means of K2CO3 in DMF. 2) Compound (VIII) can also be obtained by reaction of 2-chloro-1-(2'-cyanobiphenyl-4-ylmethyl)benzimidazole-7-carboxylic acid ethyl ester (XIII) with sodium ethoxide in refluxing ethanol.

合成路线3

1) The cyclization of aniline (I) with propionylacetic acid methyl ester (II) by means of p-toluenesulfonic acid in refluxing cyclohexane gives 2-ethylquinolin-4(1H)-one (III), which is condensed with 5-[4'-(bromomethyl)biphenyl-2-yl]-2-(triphenylmethyl)tetrazole (IV) by means of NaH in DMF, yielding 2-ethyl-4-[2'-[1-(triphenylmethyl)tetrazol-5-yl]biphenyl-4-ylmethoxy] quinoline (V). Finally, this compound is deprotected with HCl in ethanol - methanol. 2) The condensation of 4-methylphenylboronic acid (VI) with 2-bromobenzonitrile (VII) by means of Na2CO3 and PdCl2 in toluene - methanol gives 2-(4-methylphenyl)benzonitrile (VIII), which is brominated with N-bromosuccinimide (NBS) and azobis(isobutyronitrile) (AIBN) in hot chlorobenzene, yielding the bromomethyl derivative (IX). The condensation of (IX) with quinolone (III) by means of K2CO3 in N-methylpyrrolidone affords 4-(2'-cyanobiphenyl-4-ylmethoxy)-2-ethylquinoline (X), which is treated with tributyltin hydrazide in refluxing toluene to afford 2-ethyl-4-[2'-[2-(tributyltin)tetrazol-5-yl]biphenyl-4-ylmethoxy] quinoline (XI). Finally, this compound is deprotected with NaNO2 and HCl in cool water.

合成路线4

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.

合成路线5

The reaction of 2-bromo-4'-methylbiphenyl (I) with 14C labeled cuprous cyanide in refluxing DMF gives 4'-methylbiphenyl-2-carbonitrile (II), which is brominated with NBS and AIBN in refluxing CCl4 to yield the bromomethyl derivative (III). The condensation of (III) with L-valine benzyl ester (IV) by means of DIEA in hot DMF affords the N-substituted valine (V), which is acylated with pentanoyl chloride (VI) and DIEA to provide the N-acylated valine (VII). The cyclization of the cyano group of (VII) with tributyltin azide at 140 C furnishes the tetrazol derivative (VIII) which is finally debenzylated by hydrogenation with H2 over Pd/C in dioxane.

合成路线6

4) The condensation of 2,4-dimethylpyrido[2,3-d]pyrimidin-7(8H)-one (XX) with 4'-(bromomethyl)biphenyl-2-carbonitrile (XXI) by means of NaH in DMF gives 8-(2'-cyanobiphenyl-4-ylmethyl)-2,4-dimethylpyrido[2,3-d]pyrimidin-7(8H)-one (XIX), which is then cyclized with sodium azide in refluxing xylene to afford metabolite (IV).

合成路线7