The present invention is directed to a process for preparing the piperidine derivative compound 4-[4-[4-hydroxydiphenylmethyl)-1-piperidinyl]-1-hydroxybutyl]-α,α-dimethylphenylacetic acid of formula comprising the sequential steps of: (1) reacting 4-bromo-α,α-dimethyl-α-(4,4-dimethylisoxazolin-2-yl) toluene with N,N-dimethyl cyclopropylcarboxylic acid amide to provide 4-(cyclopropyl-oxo-methyl)-α,α-dimethyl-α-(4,4-dimethyloxozolin-2-yl) toluene; (2) hydrolyzing said 4-(cyclopropyl-oxo-methyl)-α,α-dimethyl-α-(4,4-dimethyloxozolin-2-yl) toluene to provide 4-(4-chloro-1-oxobutyl)-α,α-dimethylphenylacetic acid; (3) reacting said 4-(4-chloro-1-oxobutyl)-α,α-dimethylphenylacetic acid with methanol to provide methyl 4-(4-chloro-1-oxobutyl)-α,α-dimethylphenylacetate; (4) reacting said methyl 4-(4-chloro-1-oxobutyl)-α,α-dimethylphenylacetate with 4-(α,α-diphenyl)piperidinemethanol to provide methyl 4-[4-[4-(hydroxydiphenylmethyl)-1-piperidinyl]-1-oxobutyl]-α,α-dimethylphenylacetate; (5) reducing said methyl 4-[4-[4-(hydroxydiphenylmethyl)-1-piperidinyl]-1-oxobutyl]-α,α-dimethylphenylacetate to provide methyl 4-[4-[4-(hydroxydiphenylmethyl)-1-piperidinyl]-1-hydroxybutyl]-α,α-dimethylphenylacetate; and (6) hydrolyzing said methyl 4-[4-[4-(hydroxydiphenylmethyl)-1-piperidinyl]-1-hydroxybutyl]-α,α-dimethylphenylacetate to provide said 4-[4-[4-hydroxydiphenylmethyl)-1-piperidinyl]-1-hydroxybutyl]-α,α-dimethylphenylacetic acid.