Reduction of 2,2-diphenylpropionitrile (I) with LiAlH4 in Et2O produced aldehyde (II), which was further converted to cyanohydrin (III) upon treatment with KCN and p-toluenesulfonic acid. The required alpha-hydroxy ester (V) was obtained either by sequential hydrolysis of (III) to amide (IV) and then to ester (V) under acidic conditions or by direct conversion of nitrile (III) to ester (V) with boiling hydroalcoholic HCl. Subsequent saponification of the ester group of (V) with LiOH provided hydroxy acid (VI). This was finally condensed with 4,6-dimethyl-2-chloropyrimidine (VII) in the presence of NaH to give the racemic pyrimidinyl ether.

The condensation of benzophenone (I) with chloroacetic acid methyl ester (II) by means of sodium methoxide in THF gives the epoxide (III), which is treated with methanol/BF3.Et2O, yielding 2-hydroxy-3-methoxy-3,3-diphenylpropionic acid methyl ester (IV). The condensation of (IV) with 4,6-dimethoxy-2-(methylsulfonyl)pyrimidine (V) by means of K2CO3 in DMF affords 2-(4,6-dimethoxypyrimidin-2-yloxy)-3-methoxy-3,3-diphenylpropionic acid methyl ester (VI), which is hydrolyzed with NaOH in hot dioxane/water to give the corresponding free acid (VII). Finally, this compound is submitted to optical resolution, affording LU-135252. Optical resolution of (VIII), the free acid derivative of (IV), with (R)-phenylethylamine, L-proline methyl ester, (S)-1-(4-nitrophenyl)ethylamine or (S)-1-(4--chlorophenyl)ethylamine leads to the enantiomerically pure (S)-enatiomer (IX), which by reaction with 4,6-dimethoxy-2-(methylsulfonyl)pyrimidine (V) directly affords LU-135252.

A pilot plant process was further developed for the (S)-enantiomer. Darzens condensation of benzophenone (VIII) with methyl chloroacetate gave the glycidic ester (X). Epoxide opening in (X) with trimethylaluminum furnished methyl 2-hydroxy-3,3-diphenylbutyrate (XI), which was hydrolyzed to the corresponding acid (VI) by using KOH in isopropanol. Treatment of the racemic acid (VI) with (S)-1-(4-chlorophenyl)ethylamine (XII) provided the desired (S)-acid salt (XIII). This was finally condensed with 4,6-dimethyl-2-(methylsulfonyl)pyrimidine (XIV) in the presence of lithium amide to yield the title compound.