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18th May 2012 @ 01:52
To a stirring solution of MNR8-5 (7.20 g, 15.50) in toluene (150 mL) at 0 °C was added TfOH (0.7 mL, 7.75 mmol) drop-wise. The reaction was then stirred at 0 °C for 90 minutes then allowed to reach room temperature and stirred for a further 2.5 hours. As the reaction proceeded it turned a darker shade of yellow to orange. The reaction was neutralised with sat. sodium hydrogen carbonate solution, the organic fraction extracted and the aqueous fraction was washed with EtOAc (30 mL x 3). The organic layers were combined, dried, filtered and concentrated to give a thick dark orange oil

Crude reaction after 4 hours, in 100% EtOAc
MNR11-14 4 hours.JPG


Crude - 7.46 g

Crude was left in the freezer over the weekend and purified by flash column chromatography on the Monday morning.

50-100% EtOAc/Hex. early fractions that came off the column looked like starting material. This was not seen in the crude TLC.

mnr11-14 col


Frac 35-66 - 1.792 g as a sticky yellow solid - no trace of product in the NMR
mnr11-14_frac35-66.pdf

Frac 67-90 - 3.787 g as a sticky yellow solid - no trace of product in the NMR.
mnr11-14_frac67-90.pdf


**Not sure what has gone on here but it's resulted in a no product and wasting a lot of the starting material and time.

**Reaction closed - no product recovered. Time to try an alternative route to MNR26 as scaling up using this method is proving troublesome.
Attached Files
MNR11-14 4 hours.JPG
mnr11-14 col
mnr11-14_frac35-66.pdf
mnr11-14_frac67-90.pdf