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1st February 2012 @ 00:35
****Experiment concluded on 06/02/12. Conclusion pending.




Hazard and Risk Assessment
HRA KAB5-2 & KAB62


Previous Related Experiments
Preparation of 2-(3,4-Dimethoxyphenyl)ethyl isocyanide (MNR4-2)
Preparation of the PZQ analogue Ugi-intermediate (KAB5-1)
Preparation of the N-benzoyl PZQ analogue Ugi-intermediate (KAB6-1)

Following Experiments

Procedure

01/02/12
A mixture of paraformaldehyde (2.29 g, 76.2 mmol), cyclohexanecarboxylic acid (9.77 g, 76.2 mmol), 2,2-diethoxyethylamine (10.15 g, 76.2 mmol) in methanol (76 mL) was cooled in a brine ice bath. KAB4-2 (~10 g, 76 mmol) was added dropwise to the mixture at 0 °C, turning the white solution yellow. The reaction mixture was allowed to warm to room temperature and stirred from 14:00.
Reaction mixture at 1 hr


03/02/12
At 12:00 (+46 hours) The reaction mixture was concentrated under reduced pressure and the dark brown liquid residue was dissolved in ether (150 mL) then washed with water (100 mL) and brine (100 mL). The organic layer was dried over magnesium sulfate before the solvent was removed in vacuo to give crude KAB5-2 as a dark yellow-brown oil (31 g).
Concentrated reaction mixture
Dilution with ether
After washing with water. Aqueous fraction on left.
Left: combined aqueous fractions; Right: organic fraction

TLC of the crude product in EtOAc/hexane, 3:1, v/v showed two spots. One corresponding to the expected product and a polar baseline spot.
The crude product was dissolved in EtOAc (25 mL) then passed through a short silica gel column eluting with neat EtOAc. The yellow filtrate was concentrated under reduced pressure to give KAB5-2 as a dark yellow oil .
Column of crude KAB5-2
Removing solvent to give pure KAB5-2


06/02/12
The KAB5-2 final product was dried under a high vacuum before analysis by H-NMR. Yield: 28.0 g, 91%.
Drying under high vacuum
Final KAB5-2


References
[1] H. Cao, H. Liu, A. Doemling, Chemistry-a European Journal 2010, 16, 12296 (DOI: 10.1002/chem.201002046)

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NOTES 01/02/12
- Reaction mixture started turning a pale orange colour during the addition of KAB4-2.
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Linked Posts
Attached Files
Scheme KAB5-2 & KAB6-2
HRA KAB5-2 & KAB62
Table KAB5-2
Reaction mixture at 1 hr
Reaction mixture at 46 hours
Concentrated reaction mixture
Dilution with ether
After washing with water. Aqueous fraction on left.
Column of crude KAB5-2
Left: combined aqueous fractions; Right: organic fraction
Removing solvent to give pure KAB5-2
Drying under high vacuum
Final KAB5-2