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6th January 2013 @ 05:14

Reaction Scheme

Overall Yield: 1.73 g, 13.9 mmol, 55% yield.

DMF (12.0 mL) was stirred under a nitrogen atmosphere in an ice-bath. Phosphoryl chloride (2.83 mL, 30.5 mmol, 1.2 equiv.) was added and the reaction stirred for 25 minutes. Reaction still colourless. A solution of pyrrole AEW 32-1 (2.4 g, 25.3 mmol, 1 equiv.) in DMF (12 mL) was added dropwise over 5 minutes. The reaction was removed from the ice-bath and allowed to warm to room temperature. TLC taken after 1h15. Deep brown reaction mixture turned deep purple on mini work-up with water and ethyl acetate:reaction was complete by TLC, no SM and faint spot visualised in potassium permanganate at Rf 0.19, not very clear in photo. Poured over ice (250 ml), turned deep purple. pH adjusted to 6 (approx. 20% NaOH) and the resulting rusty coloured solution left stirring overnight. In the morning, the pH remained at 6, the pH was adjusted to 11 (approx. 20% NaOH), and the cloudy brown mixture was extracted with EtOAc (2 x 100 mL), washed with water (30 mL), brine, dried over MgSO4, filtered and evaporated. A beige solid crashed out of solution on evaporation. The ppt was collected by filtration to give (814 mg, 6.62 mmol, 26% yield) of a beige solid. A second batch was precipitated from EtOAc to give (915 mg, 7.3 mmol, 29% yield) of a slightly darker solid.

1H NMR:

mislabelled as AEW 34-1 but really AEW 33-1

AEW 34-1 char.zip

TLC, 50% EtOAc in hexane, UV then K2MnO4:

AEW 33-1 TLC, potmang.JPG
AEW 33-1 TLC UV.JPG

Hazard and Risk Assessment: See TCMDC_AP AEW 2-1, different starting material, 2,5-dimethylpyrrole which is: Flammable. Toxic by inhalation, in contact with skin and if swallowed. Irritating to eyes, respiratory system and skin. Risk Class 2, HU and Sl.

Attached Files
AEW 33-1.png
AEW 33-1 TLC UV.JPG
AEW 33-1 TLC, potmang.JPG
AEW 33-1 quench.JPG
AEW 33-1 ph6.JPG
AEW 34-1 char.zip