A solution of 2 (0.91 g, 3.46 mmol) in anhydrous tetrahydrofuran (15 mL) was stirred under nitrogen at −78° C. and 2.5M n-butyllithium in hexanes (1.38 mL, 3.46 mmol) was added at such a rate that the temperature did not exceed −70° C. Stirring was continued at −78° C. for 1 hr when a solution of 2-(benzyloxy)biphenyl-3-carbaldehyde (1.0 g, 3.46 mmol) in tetrahydrofuran (5 mL) was added at such a rate that the temperature did not exceed −65° C. Stirring was continued at −78° C. for 20 min, then for 2 hr at room temperature. The reaction mixture was poured on saturated ammonium chloride (150 mL) and extracted with ethyl acetate (150 mL). The organic extract was washed with water (2×100 mL), dried over sodium sulfate and stripped. The crude 3 was used as such in the next step.
