Sodium hydride → 4-(Dimethylamino)pyridine

##STR28## tert-Butyl 3-carbethoxy-1-(2-(4-propylphenyl)ethyl)-2-cyclopentene-1-carboxylate. Sodium hydride (16 mg of 60% oil dispersion, 0.40 mmol) was added to a solution of 102 mg (0.35 mmol) of tert-butyl 2-formyl-4-(4-propylphenyl)butanoate in 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (1.5 mL). After 20 min., 1-carboethoxycyclopropyl triphenylphosphonium tetrafluoroborate (193 mg, 0.42 mmol) was added to the pale yellow solution and stirring was continued overnight at room temperature. The solution was then partitioned between hexane (25 mL) and 2N aq. HCl (25 mL). The organic layer was washed with water (15 mL) and saturated aq. NaCl (15 mL), dried (Na2SO4), decanted, and evaporated. The residue was purified by flash column chromatography on silica gel (8 g), eluting with 100 mL of 5% EtOAc/hexane, to give the title compound as 52 mg (38% yield) of colorless oil.