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6th August 2012 @ 00:52
Monitoring reaction at -5 °C with the idea that maybe complexes will be more stable at these temperatures and catalyse the reaction ahead of free Yb(OTf)3. To a solution of MNR42-1 (0.2 g, 0.64 mmol) in dry acetonitrile (20 mL, HPLC grade stored over 3 Å molecular sieves for 24 hours) and 3 Å molecular sieves (3 g, dried in microwave) under argon at -5 °C, was added was added acetyl chloride (0.08 mL, 1.15 mmol), 2,6-lutidine (0.10 mL, 0.89 mmol, stored over 3 Å molecular sieves) and PZQ (0.02 g, 0.06 mmol). Yb(OTf)3 solution (0.128 g, in THF (15 mL)) (2.3 mL, 0.02 g, 0.03 mmol) was added and the reaction was stirred at -5 °C and followed by LCMS analysis. The reaction was monitored by LCMS by taking samples carrying out the following procedure. 0.1 ml was removed from the reaction mixture using a disposable syringe and transferred to a vial. EtOAc (0.4 mL) and sodium hydrogen carbonate saturated solution (0.2 mL) was added and the vial capped and shaken. The layers were allowed to separate and the organic layer was carefully removed by pipette and transferred to another vial and concentrated to dryness under reduced pressure. Acetonitrile (1.8 mL) was added and the mixture shaken, 0.06 mL was transferred to a LCMS vial and acetonitrile 0.3 mL). Reaction on at 915am Samples taken at 1015 - 1 hour 1215 - 3 hours 1415 - 5 hours 1615 - 7 hours 1815 - 9 hours 1915 - 10 hours 0915 - 24 hours Plotting the data shows that the reaction is done to
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