TCMDC_ArylPyrrole

 

Product obtained and used as a crude mixture.

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Synthesis of side-chain of TCMDC-123794 4-aminoantipyrine.



Reaction start time: 1730 EST 21/09/11
Crude PMY 7-1 ("27.0 mmol") was stirred in toluene (40 mL). The material crystallised and was dissolved by heating. 4-aminoantipyrine (5.73 g, 28.2 mmol, 1.05 equiv.) was added and the reaction heated to reflux. After 15.5 hours, the reaction was cooled. Orange solid and almost colourless solvent. Dissolved by addition of EtOAc and DCM and the whole concentrated a pale orange foam (7.67 g). ¹H NMR consistant with expected product and excess 4-aminoantipyrine. Dissolved in water (approx. 150 mL) and washed with EtOAc (3 × 50 mL). Aqueous layer concentrated under reduced pressure to a tan foam (6.66 g, 94% of theory). Compounds still contains impurity peaks at 2.84 and 2.16 ppm if these correspond to methyl signals then there is approx. 14% impurity present.

30/09/11 Purification by column (0-10% MeOH/DCM). 2 fractions: PMY 9-1-B clean by TLC (0.71 g) and PMY 9-1-A unclean (5.67 g). acetone/hexane/EtOAc based systems seem to give worse separation. Worth persevering with systems and other methods to avoid DCM in future.

Solubility:
4-aminoantipyrine:
Soluble in: MeCN, DCM, water, EtOH, EtOAc

PMY 9-1:
Soluble in: MeCN, DCM, water (readily), EtOH
Not soluble in: EtOAc, toluene

TLC (15% MeOH/DCM) visualised with UV and vanillin:

Fractions 0-10 (5.67 g), fractions 11-30 (0.71 g)

NMR:


Risk and Hazard Assessment:


See also:
Synthesis of Glycolic Acid Acetonide (PMY 7-1)