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22nd November 2011 @ 07:30
Samples MNR12-1 and MNR12-2 were combined and purified by column chromatography (silica gel, ethyl acetate:hexane 50-100 %). The products KAB2-1a and KAB2-1b were observed by TLC in ethylacetate before the fractions were combined and the solvent removed under reduced pressure.

Scheme%202-1.png

Yield
KAB2-1a: 41 mg (fractions 77-88)
KAB2-1b: 58 mg (fractions 7-12)
Everything else: 95 mg

Total recovery: 194 mg
Amount loaded: 180 mg

TLC of crude MNR12-1 and MNR12-2 in ethyl acetate
Stain: KMnO4
Crude TLC

TLC of fractions 77-89



Characterisation

22/11/11: H-NMR was recorded for KAB2-1a. Very messy - Needs further tweaking/processing, possibly changing temp and diluting further. Also has ethyl acetate contamination.
HNMR KAB2-1a

note: The spectrum similar to the SciFinder predicted H-NMR.

23/11/11: The NMR sample prepared yesterday was further diluted in CDCl3 and the spectrum re-recorded. It was slightly cleaner. Need to process the data, results pending.
The KAB2-1 samples in CDCl3 were recombined and the solvent removed under reduced pressure. giving a clear oil, which was placed in the freezer overnight to promote crystallisation.

24/11/11:
8:17 am - No crystallisation yet
Photo.jpg

The KAB2-1 sample was removed from the freezer and put under high vacuum. The remaining fractions (1-6, 13-76 and 89-111) were combined and the solvent removed to give a slightly yellow solid with a mass of 95 mg. The total recovery was 108 % of the amount loaded. Possible silica contamination from the column.

7:11 pm - Sample KAB2-1a was returned to freezer


24/11/11:
8:17 am - KAB2-1a Still no crystallisation.

28/11/11:
8:13 am - KAB2-1a Still no crystallisation. Sample removed from freezer and left at room temperature.

28/11/11:
Sample no longer a gel, but a yellow solid. Attempt at recrystallisation from toluene and hexane.

08/12/11:
Formation of small yellow crystals. Flask kept at room temperature.

15/12/11:
Crystallisation complete. The small yellow crystals were washed in hexane then filtered.

16/12/11:
1H-NMR recorded.

03/01/12:
Yield: 27.8 mg, 19.3%
Rough m.p.: 109-120 C
Final KAB2-1


Recovery and yield for the purification procedure was poor. As of 23/01/12, no characterisation performed on the recovered crystals.

Links
More Information here
Attached Files
HNMR KAB2-1a
Crude TLC
Scheme KAB2-1
KAB2-1 out of freezer
Final KAB2-1