A 1.6M solution of n-butyllithium in hexane (91.8 mL, 147 mmol) was added to a -20° C. solution of diisopropylamine (21 mL, 150 mmol) in THF (480 mL). Hexamethylphosphoramide (56 mL) was added and the mixture maintained at -20° C. while a solution of 3-(3,4-dimethoxyphenyl)propionic acid (15.1 g, 72 mmol) in THF (75 mL) was added. The resulting solution was stirred at room temperature for one hour, and then cooled to -50° C. A solution of 2-(3,4-dimethoxyphenyl)-2-isopropyl-2-(3-iodopropyl)acetonitrile (22, 27.9 g, 72 mmol) was added, and the mixture allowed to warm to room temperature while stirring for 12 hours. The resulting mixture was added to water, acidified with HCl, and extracted three times with ether. The organic layer was washed with aqueous Na2SO3 and brine, dried over Na2SO4, and evaporated to yield 1-(3,4-dimethoxyphenyl)-2-carboxy-6-cyano-6-(i-propyl)-6-(3,4-dimethoxyphenyl)hexane (23, 31 g) as a thick oil.
