Compound 7

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Compound data: NMR

Compound data: Crystallographic data

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

According to General Procedure A outlined for compound 6, cyclohexyl pinacol boronic ester (50 mg, 0.24 mmol, 1.0 equiv) and 4-trifluoromethylphenyl triflate (84 mg, 0.29 mmol, 1.2 equiv) were coupled to give a crude residue (>98:2 d.r. by crude NMR) that was purified by flash column chromatography (SiO₂; 80:20 pentane:DCM) to afford the corresponding cyclobutane 7 (75 mg, 77 %, >98:2 d.r.) as a white solid. m.p.: 106 – 109 °C (pentane). TLC: R_f = 0.30 (80:20 pentane:DCM). ¹H NMR (400 MHz, CDCl₃) δ 7.52 (d, J = 8.3 Hz, 2H, 2× ArH), 7.28 (d, J = 8.3 Hz, 2H, 2× ArH), 3.39 (m, 1H, ArCCH), 2.60 – 2.55 (m, 2H, ArCH(CH^aH^b)₂), 1.88 – 1.83 (m, 2H, ArCH(CH^aH^b)₂), 1.74 – 1.67 (m, 5H, 2× CH₂, CH^aH^b), 1.35 – 0.93 (m, 6H, 2× CH₂, CH, CH^aH^b), 1.31 (s, 12H, Bpin) ppm. ¹³C NMR (101 MHz, CDCl₃) δ 150.8 (ArC), 126.8 (ArCH), 125.1 (q, J_C–F = 3.8 Hz, ArCH), 83.3 (OC(CH₃)₂), 49.2 (CH), 37.4 (ArCCH(CH₂)₂), 35.6 (ArCCH), 29.1 (CH₂), 26.9 (CH₂), 26.9 (CH₂), 25.0 (OC(CH₃)₂) ppm. CF₃ and ArCCF₃ were low intensity and so were not picked. ¹⁹F NMR (377 MHz, CDCl₃) δ –62.2 ppm. HRMS (m/z): (ESI) calc’d for C₂₃H₃₂BF₃NaO₂ [M+Na]⁺: 431.2344, found: 431.2335. IR (solid state) ν_max: 2924, 2854, 1615, 1321, 1158, 1120, 1064 and 834 cm⁻¹. X-ray Crystal Structure: CCDC number: 1847415.