Compound 31

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InChIKey CJNZDNNYWALDDV-ZQFMVCDBSA-N

Compound data: NMR

Compound data: Crystallographic data

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

In a flame-dried Schlenk tube, 1-bromonaphthalene (0.03 mL, 0.20 mmol, 2.10 eq.) was dissolved in anhydrous Et₂O (1 mL) at 0 °C under an atmosphere of nitrogen. A solution of n-BuLi (1.60 M in n-hexane, 0.12 mL, 0.20 mmol, 2.10 eq.) was added and the resulting suspension was stirred at the same temperature for 1 h. A solution of boronic ester 18 (50 mg, 0.09 mmol, 1.00 eq.) in anhydrous Et₂O (1 mL) was added dropwise at 0 °C over 10 min. After the addition, the mixture was stirred at the same temperature for 2 h. Solvents were removed in situ and the residue was dissolved in a mixture of dry MeOH and anhydrous THF (2:1, 1 mL) at –‍78 °C under an atmosphere of nitrogen. A solution of NBS (80 mg, 0.45 mmol, 4.80 eq.) in dry MeOH (2.5 mL) was added dropwise at the same temperature. After the addition, the acetone/dry ice bath was removed and the reaction mixture was stirred at room temperature for 1 h. A saturated aqueous solution of Na₂S₂O₃ (5 mL) was added. After 5 min, the suspension was extracted with Et₂O (3 × 5 mL). The organic layers were combined, washed with brine, dried over MgSO₄, filtered and concentrated under reduced pressure. The yellow residue was purified by flash column chromatography (n-pentane:Et₂O 100:0→99.5:0.5) to give compound 31 (12 mg, 24%) as a white solid. . TLC: R_f = 0.69 (n-pentane:Et₂O 95:5). m.p.: 157 – 159 °C (acetonitrile). ¹H NMR (500 MHz, Chloroform-d): δ 8.17 (2H, dd, J = 8.2, 1.6 Hz, H2), 7.85 (2H, dd, J = 7.6, 2.0 Hz, H5), 7.68 (2H, dd, J = 8.0, 1.2 Hz, H7), 7.48 (2H, ddd, J = 8.2, 6.6, 2.0 Hz, H3), 7.45 (2H, ddd, J = 7.6, 6.7, 1.6 Hz, H4), 7.43 (2H, dd, J = 8.0, 7.3 Hz, H8), 7.36 (2H, dd, J = 7.2, 1.2 Hz, H9), 3.50 (2H, m, H11), 2.10 (2H, m, H13), 1.46 (2H, dqd, J = 8.8, 6.8, 2.5 Hz, H17), 1.37 (2H, m, H19), 1.30 (6H, d, J = 6.9 Hz, H12), 1.07 (2H, dqd, J = 8.8, 6.8, 2.9 Hz, H15), 0.92 (6H, d, J = 6.7 Hz, H14), 0.67 (6H, d, J = 6.8 Hz, H16), 0.55 (6H, d, J = 6.8 Hz, H18), 0.33 (6H, m, H20) ppm. ¹³C NMR (126 MHz, Chloroform-d): δ 144.3 (C10), 134.1 (C6), 132.0 (C1), 129.1 (C5), 126.1 (C7), 125.7 (C4 or C8), 125.6 (C8 or C4), 125.2 (C3), 124.1 (C9), 123.4 (C2), 39.4 (C13), 37.2* (C11), 36.3 (C15), 35.6 (C17), 35.5 (C19), 20.8 (C12), 12.3 (C16), 12.1 (C14), 11.9 (C18 or C20), 11.9 (C20 or C18) ppm. *shift value determined by HSQC correlation. HRMS (m/z): (MALDI⁺) calc’d. for C₄₀H₅₄Na [M+Na]⁺: 557.4118; found 557.4110. IR (ν_max): 3049, 2966, 2925, 1453, 1382, 1260, 1083, 778 cm⁻¹. [α]_D²⁵: +45 (CHCl₃, c = 1.0).