Reaction Steps
To a solution of NaIO4 (5.9503 g, 27.82 mmol) in water (40 mL) was added RuCl3 hydrate (0.0526 g, 0.25 mmol) followed by a solution of crude N-(6′-bromo-1′-(1-ethoxyvinyl)-4-methoxy-1′,3′-dihydrospiro[cyclohexane-1,2′-indene]-1′-yl)-2-(trimethylsilyl)ethanesulfonamide (9) (1.0894 g), obtained as described above, in EtOAc (60 mL). The resulting mixture was vigorously stirred at room temperature for 30 min and LC-MS indicated the disappearance of starting material. The organic layer was separated and the aqueous layer was extracted twice with EtOAc. The combined organic layers was dried over Na2SO4, filtered and evaporated. The residue was purified by chromatography on silica gel eluted with hexanes/ethyl acetate to afford ethyl 6′-bromo-4-methoxy-1′-(2-(trimethylsilyl)ethylsulfonamido)-1′,3′-dihydrospiro[cyclohexane-1,2′-indene]-1′-carboxylate (10) (0.5329 g, 50% in two steps). LC-MS tR=2.27 min in 3 min chromatography, m/z 568, 570 (MNa+), 333, 335; 1H NMR (400 MHz, CDCl3) δ 7.90 (s, 1H), 7.41 (d, J=7.9 Hz, 1H), 7.12 (d, J=8.2 Hz, 1H), 4.41-4.25 (m, 2H), 3.32 (s, 3H), 3.08-3.02 (m, 2H), 2.80 (d, J=15.8 Hz, 1H), 2.16-2.04 (m, 3H), 1.91-1.87 (m, 2H), 1.80-1.72 (m, 1H), 1.40-1.22 (m, 7H), 0.95-0.88 (m, 1H), 0.80-0.72 (m, 1H), 0.65-0.57 (m, 1H), −0.17 (s, 9H); 13C NMR (100 MHz, CDCl3) δ 170.13, 142.21, 140.91, 132.97, 132.25, 126.52, 119.45, 78.49, 75.10, 61.87, 55.79, 53.06, 50.92, 38.15, 28.64, 28.38, 28.33, 27.82, 14.18, 9.98, −2.28.
