合成路线1

The reduction of the chiral propionic acid (VII) with NaBH4 in THF gives the primary alcohol (XXIX), which by reaction with SOCl2 and pyridine in CHCl3 yields the chloride (XXX). Condensation of (XXX) with the butyrolactone intermediate (XXVII) by means of Mg and dibromoethane affords the ketonic adduct (XXXI). Reduction of the exocyclic carbonyl group of (XXXI) with NaBH4 in THF/ methanol provides a 3:1 diastereomeric mixture of the desired chiral alcohol (XXXII) and its OH-epimer (XXXIII) that are separated by flash chromatography. Reaction of (XXXII) with MsCl and TEA, followed by treatment with NaN3, affords the azido derivative (XXXIV), which is condensed with 4-amino-3,3-dimethylbutyramide (XIX) by means of 2-hydroxypyridine and TEA to provide the adduct (XXXV). Finally, the azido group of (XXXV) is reduced with H2 over Pd/ in MeOH to yield the target amino alcohol. An extensive study on the stereoselective reduction of the ketonic adduct (XXXI) has been performed. No better diastereoselectivity than 3:1 has been obtained for the synthesis of the chiral alcohol (XXXII). However, excellent diastereoselectivity (97:3) has been obtained for the synthesis of its OH-epimer, alcohol (XXXIII), with K-selectride in THF, which could potentially provide access to the target amino alcohol via a double inversion protocol.

合成路线2

The chiral azido intermediate (XXXIV) can also be obtained as follows: Reaction of (+)-pseudoephedrine isovaleramide (XLIII) with allyl bromide (XXI) by means of LDA in THF gives the pentenoyl amide (XLIV), which is treated with NBS in DME/water to yield the spiro compound (XLV). Hydrolysis of the bromomethyl group of (XLV) with tetrabutylammonium acetate and K2CO3 affords the carbinol (XLVI), which is oxidized to aldehyde (XLVII) with SO3/pyridine and TEA in DMSO/dichloromethane. Condensation of (XLVII) with the propyl chloride intermediate (XXX) by means of Mg, dibromoethane and CeCl3 in refluxing THF provides the already reported chiral hydroxylactone (XXXII), which is treated first with 4-bromobenzenesulfonyl chloride and then with NaN3 to give the desired azido derivative (XXXIV).

合成路线3

The condensation of the chiral chloro derivative (I) with 5-chloro-[2(S)-isopropyl]-4-pentanoic acid methyl ester (II) by means of Mg and dibromoethane in THF gives the chiral octenoic ester (III) which is converted to the corresponding acid (IV) by means of LiOH in THF/methanol/water. The reaction of (IV) with NBS in dichloromethane yields the bromolactone (V), which is treated with LiOH in isopropanol to yield the epoxide (VI). This compound, without isolation, is treated with HCl in the same solvent to afford the chiral hydroxylactone (VII). The reaction of the OH group of (VII) with MsCl and pyridine in toluene provides the mesylate (VIII), which is treated with NaN3 in hot 1,3-dimethylperhydropyrimidin-2-one to give the azido derivative (IX). The condensation of (IX) with 3-amino-2,2-dimethylpropionamide (X) by means of 2-hydroxypyridine in hot TEA yields the carboxamide (XI). Finally, the azido group of (XI) is reduced with H2 over Pd/C in tert-butyl methyl ether to provide the target Aliskiren.

合成路线4

合成路线5