Reaction Steps
7-(3-Methyl-but-2-enyl)-3-tributylstannanyl-indole-1-carboxylic acid tert-butyl ester (203) was prepared according to the procedure developed by our group.23 Stannane 203 (1.146 g, 1.995 mmol) and 2-bromo-3-(tert-butyl-dimethyl-silanyloxy)-6-(tert-butyl-dimethyl-silanyloxymethyl)-pyran-4-one (600 mg, 1.33 mmol) were dissolved in toluene (10 mL). Tetrakis(triphenylphosphine)palladium (77 mg, 0.067 mmol) was added. Argon was bubbled through the resulting solution for 15 min to remove oxygen. The mixture was heated to 90° C. and stirred for 20 h. The mixture was cooled to room temperature, diluted with ether and washed with saturated aqueous KF solution several times. The organic layer was dried over Na2SO4 then solvent removed under vacuum. After flash column chromatography, the desired product was obtained as a light yellow oil (532 mg, 61%). 1H NMR (CDCl3): δ 0.15 (6H, s), 0.29 (6H, s), 0.92 (9H, s), 0.96 (9H, s), 1.65 (9H, s), 1.70 (3H, s), 3.77 (2H, d, J=6.6 Hz), 4.60 (2H, s), 5.24 (1H, m), 6.48 (1H, s), 7.2-7.3 (2H, m), 7.86 (1H, m), 8.24 (1H, s). 13C NMR (CDCl3): δ −5.2, −2.8, 18.2, 18.5, 19.2, 22.5, 26.0, 26.5, 28.2, 31.6, 33.6, 61.8, 84.7, 111.0, 119.5, 123.0, 124.1, 126.3, 127.2, 129.2, 129.6, 130.9, 133.4, 134.2, 137.6, 141.5, 149.2, 149.6, 165.0, 175.3. IR (KBr): 3150, 2895, 1576, 1269, 1151 cm−1. HRMS (EI): m/z Caled. for C36H55NO6Si2 [M+] 653.3568, found 653.3577.
