Compound 6

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InChIKey ARHNJSZZPOYVQL-BXQOXDDISA-N

Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.

Polymethylhydrosiloxane (5.27 mL) was added to a solution of 7 (6.48 g, 0.0086 mol) in PhCH₃ (175 mL) followed by formic acid (0.98 mL, 0.026 mol). Bis(dibenzylideneacetone)palladium(0) chloroform adduct (89.0 mg, 0.086 mmol) in PhCH₃ (90 mL) was added via cannula, and the flask containing catalyst was rinsed with PhCH₃ (85 mL, 0.025 M final concentration). The reaction was stirred at r.t. 1 h during which time the solution changed from deep purple to orange and TLC analysis indicated complete consumption of starting material. The remaining formic acid was neutralized by addition of solid NaHCO₃ followed by decanting and concentrating the supernatant to 15 mL. The resulting solution was loaded directly onto a silica gel column (0% to 7% EtOAc/petroleum ether) to provide 5.19 g 6 (80%) as a pale yellow foam. TLC: R_f = 0.40 (1:9 ethyl acetate:pentane), one spot. ¹H-NMR (500 MHz, CDCl₃, residual solvent peak referenced to 7.24 ppm) δ 7.33-7.16 (m, 8H), 7.09-7.06 (m, 2H), 6.20 (s, 1H), 5.95 (ddd, J=16.5, 10.7, 9.4, 1H), 5.24 (s, 1H), 5.21 (dd, J=7.8, 1.8, 1H), 4.97 (d, J=11.2, 1H, AB), 4.51 (s, 1H), 4.40 (d, J=11.2, 1H, AB), 4.27 (dd, J=11.0, 9.3, 1H), 3.81 (dd, 5.9, 2.0, 1H), 3.72 (d, J=11.2, 1H, AB), 3.44 (dd, J=9.3, 2.0, 1H), 3.36 (d, J=11.2, 1H, AB), 2.77 (ddd, J=9.4, 5.7, 3.9, 1H), 2.62-2.55 (m, 1H), 2.57 (dd, J=12.3, 9.3, 1H), 2.42 (dd, J=10.9, 9.6, 1H), 2.18 (ddd, J=13.4, 6.3, 1.6, 1H), 2.03 (d, J=1.7, 1H), 2.00 (ddd, J=10.7, 8.2, 6.3, 1H), 1.66 (dd, J=12.1, 3.3, 1H), 1.48-1.39 (m, 1H), 1.44 (s, 3H), 1.38 (s, 3H), 1.31 (d, J=7.0, 3H), 0.90 (s, 9H), 0.01 (s, 3H), -0.04 (s, 3H) ppm. ¹³C-NMR (125 MHz, CDCl₃) δ 151.69, 138.80, 138.08, 135.79, 128.65, 128.15, 128.08, 127.20, 127.18, 126.48, 120.39, 118.47, 110.34, 86.72, 85.49, 82.86, 79.00, 74.78, 74.55, 72.97, 66.24, 60.44, 54.89, 51.17, 42.46, 37.48, 30.59, 29.67, 27.40, 26.73, 25.87, 24.05, 18.32, -5.18, -5.35 ppm. FTIR (thin film) 3551, 3027, 2953, 2928, 2854, 1492, 1454, 1380, 1369, 1332, 1297, 1254, 1223, 1187, 1149, 1113, 1082, 1059, 1097, 1028, 993, 957, 918, 905, 884, 852, 836, 778, 744, 698, 630 cm^-1. HRMS: Calculated for C₄₁H₅₅BrNaO₆Si (M+Na⁺): 773.2849; Found: 773.2814. [α]_D = 115.9 ° (c 0.50, CHCl₃). Elemental analysis: Calculated for C₄₁H₅₅BrO₆Si: %C = 65.50, %H = 7.37; Found: %C = 65.45, %H = 7.58.