To a solution of 1-ethyl-4-hydroxy-1,3,4,9-tetrahydropyrano[3,4-b]indole-1-acetic acid methyl ester (1 g, 3.6 mmol) in 60 mL of dry methylene chloride at -78° C. under nitrogen was added TiCl4 in one portion and then after ~10 minutes, a solution of benzyl magnesium bromide in ether was added in one portion and the reaction mixture was allowed to stir at -78° C. for ~30 minutes. The reaction was quenched with methanol (3 mL) at -78° C. and then poured into water (10 mL). The two layers were separated and the aqueous layer was then extracted with methylene chloride (2×100 mL), dried over magnesium sulfate and concentrated in vacuo. The crude product was passed through a pad of silica gel, eluting with 10% EtOAc in hexane to give 0.67 g (51.5%) of the product as an oil, which had isomer ratio of 75:25 by HPLC.
