[CH3:1][O:2][C:3](=[O:21])[CH2:4][C:5]1([CH2:19][CH3:20])[C:10]2[NH:11][C:12]3[C:17]([C:9]=2[CH:8](O)[CH2:7][O:6]1)=[CH:16][CH:15]=[CH:14][CH:13]=3.[Br-].[Mg+2].[Br-]>C(Cl)Cl.CCOCC.Cl[Ti](Cl)(Cl)Cl>[CH3:1][O:2][C:3](=[O:21])[CH2:4][C:5]1([CH2:19][CH3:20])[C:10]2[NH:11][C:12]3[C:17]([C:9]=2[CH:8]([CH2:9][C:17]2[CH:12]=[CH:13][CH:14]=[CH:15][CH:16]=2)[CH2:7][O:6]1)=[CH:16][CH:15]=[CH:14][CH:13]=3
To a solution of 1-ethyl-4-hydroxyl-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 banzyl magnesium bromide in ether was added in one portion and the reaction mixture was allowed to stir at -78° C. for ~30 minutes. The reacton 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.
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