A stirred, cooled (−78° C.) solution of 6-(2,2-dibromo-vinyl)-2-cyclopropyl-4,4-dimethyl-1,2,3,4-tetrahydroisoquinoline-6-carboxaldehyde (Intermediate 26, 0.1 8 g, 0.47 mmol) in tetrahydrofuran (2 mL) was treated with 1.6M solution of n-butyl lithium (0.6 mL, 0.96 mmol) under argon. The reaction mixture was allowed to warm to −20° C. over 1.5 h, quenched with saturated aqueous ammonium chloride solution and extracted with diethyl ether (×2). The combined organic phase was dried over anhydrous magnesium sulfate, filtered and evaporated in vacuo to afford the title compound as an oil (0.1 g, 94%).
