Compound 3o

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Compound data: HPLC

Compound data: 1H NMR

Compound data: 13C NMR

Compound data: 19F NMR

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

1o was fluorinated following general procedure A described for compound 3a, using benzene as solvent. Due to the volatility of the product, the yield was determined by ¹H NMR analysis of the crude product using CH₂Br₂ (0.2 mmol, 14 uL) as the internal standard (36% NMR yield of 3o). Pure analytical sample was isolated by additional preparative TLC using hexanes/ethyl acetate as eluent (86% ee). The ee value was determined by HPLC analysis on a Chiralcel AS-H column (2% isopropanol in hexanes, 0.5 mL/min) with retention time of 14.1 min (major) and 20.1 min (minor). Absolute stereochemistry was assigned based on the X-ray crystallographic data of compound 5a. ¹H NMR (600 MHz, CDCl₃): δ 10.60 (d, J = 1.7 Hz, 1H), 8.44 (d, J = 8.0 Hz, 1H), 7.81 (d, J = 8.0 Hz, 1H), 6.19 (dq, J = 47.7, 6.6 Hz, 1H), 1.87 (dd, J = 24.1, 6.6 Hz, 3H). ¹³C NMR (150 MHz, CDCl₃): δ 189.35 (dd, J = 11.3, 4.8 Hz), 160.91 (d, J = 23.8 Hz), 150.40 (qd, J = 35.4, 1.2 Hz), 139.21 (d, J = 0.8 Hz), 131.63, 120.75 (q, J = 274.9 Hz), 120.34 (qd, J = 2.4, 0.9 Hz), 91.06 (d, J = 170.2 Hz), 21.18 (d, J = 23.0 Hz). ¹⁹F NMR (376 MHz, CDCl₃): δ –68.71, –168.94. HRMS (ESI-TOF): m/z calculated for C₉H₈F₄NO⁺ [M+H]⁺ 222.0537, found 222.0532.