Compound 15
2-((1s,3s)-1-cyclohexyl-3-(2,6-dimethylphenyl)cyclobutyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane
From: Carbopalladation of C–C σ-bonds enabled by strained boronate complexes
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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 2,6-dimethylphenyl triflate (73 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; 70:20:10 pentane:PhMe:DCM) to afford the corresponding cyclobutane 15 (58 mg, 66 %, >98:2 d.r.) as a white solid. m.p.: 124 – 126 °C (pentane). TLC: Rf = 0.30 (70:20:10 pentane:PhMe:DCM). 1H NMR (400 MHz, CDCl3) δ 6.97 – 6.90 (m, 3H, 3× ArH), 3.58 – 3.49 (m, 1H, ArCCH), 2.72 – 2.67 (m, 2H, ArCH(CHaHb)2), 2.32 (s, 6H, 2× ArCCH3), 2.10 – 2.04 (m, 2H, ArCH(CHaHb)2), 1.71 – 1.63 (m, 5H, 2× CH2, CHaHb), 1.37 – 0.90 (m, 6H, 2× CH2, CH, CHaHb), 1.32 (s, 12H, Bpin) ppm. . 13C NMR (101 MHz, CDCl3) δ 142.0 (ArC), 136.6 (ArCCH3), 129.1 (ArCH), 125.4 (ArCH), 83.2 (OC(CH3)2), 49.4 (CH), 39.1 (ArCCH(CH2)2), 36.0 (ArCCH), 29.5 (CH2), 27.0 (CH2), 26.9 (CH2), 24.9 (OC(CH3)2), 22.1 (2× ArCCH3) ppm. . HRMS (m/z): (ESI) calc’d for C24H37BNaO2 [M+Na]+: 391.2783, found: 391.2785. IR (solid state) νmax: 2974, 2914, 2842, 1461, 1378, 1296, 1141, 969, 867, 767 and 668 cm−1. X-ray Crystal Structure: CCDC number: 1835073.
