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9th August 2012 @ 00:56
Mnr: 41-50
Repeat of MNR41-13 but using a new clean vial to carry out the reaction in. Also, reagents were measure out using a plastic spatula and plastic Gilson tips. The reaction was also shaken on the shaker to avoid the use of a stirring bar.

MNR41-4%20scheme.png
mnr41-14%20table.PNG

To a solution of MNR42-1 (0.1 g, 0.32 mmol) in dry acetonitrile (10 mL, HPLC grade stored over 3 Å molecular sieves for 24 hours) and 3 Å molecular sieves (1.5 g, dried in microwave) under argon at 0 °C, was added was added acetyl chloride (0.041 mL, 0.57 mmol), 2,6-lutidine (0.052 mL, 0.48 mmol, stored over 3 Å molecular sieves) and PZQ (0.01 g, 0.03 mmol). The reaction was then shaken at room temperature (19 °C) for 1 hour.

After 1 hour a sample was taken for mini workup and LCMS. The reaction was left to shake.

LCMS

mnr41-14_75mins.pdf


LCMS after 75 mins showed significant product.

Work Up

The mixture was filtered to remove the molecular sieves and washed with EtOAc (20 mL). The filtrate was washed with saturated sodium bicarbonate solution (25 mL). The aqueous layer was extracted with ethyl acetate (3 × 30 mL). The organic fractions were combined, dried over MgSO4, filtered and concentrated under reduced pressure to yield a yellow solid (0.096 g)

The crude was then taken up in IPA (3 ml) in an attempt to crystallise the product overnight. Crystals washed with IPA in the morning.

0.049 g

NMR

mnr41-14.pdf


NMR shows mainly product but still some starting material

Conclusions

* This rules out the potential of contaminated glassware - traces of Yb in the flask
* This rules also rules out the potential for traces of metal coming from anther source, spatula, stir bar, needles.
* Still the potential for the reaction to be catalysed by the molecular sieves (slightly acidic)
* Is the PZQ doing anything?

- requires further control experiments testing to above variables
Attached Files
mnr41-14 table.PNG
mnr41-14_75mins.pdf
mnr41-14.pdf