TCMDC_ArylPyrrole

 

Product obtained in 12% yield.

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Condensation of 2-phenyliminothiazolidin-4-one (PMY 13-1) and PMY 2-4 to obtain the iminothiazolidinone substituted 4-fluorophenylpyrrole analogue of "near neighbours". Hydrolysis of intermediate n-acyl species to obtain the desired product.



Reaction start time: 1430 07/11/11
PMY 2-4 (200 mg, 0.92 mmol, 1 equiv.), PMY 13-1 (177 mg, 0.92 mmol, 1 equiv.) and sodium acetate (251 mg, 1.84 mmol, 2 equiv.) were heated at 100 °C in AcOH/Ac₂O (5:1, 15 mL) for 18 hours. The reaction was then poured onto ice (melted total volume 80 mL) and the reaction allowed to stand for 2.5 hours. The mixture was cooled in ice and solid NaOH added slowly until pH 14. The reaction turned from green/purple to clear solution with dark solid. The mixture was allowed to stand at room temperature for 30 minutes, then extracted with EtOAc (3 × 30 mL). The organic extracts (dark green conc, green/yellow dilute) were washed with brine and concentrated under reduced pressure (0.24 g approx, big flask). Chromatography (0-1.5% MeOH/DCM) gave mostly mixed fractions and potential product yellow solid, PMY 14-3-A (34 mg, 9%). The mixed fractions containing acyl species by TLC, product and impurities was dissolved in EtOH (5 mL) and 2M NaOH (approx 2 mL) added. After 20 minutes, 10% citric acid added to neutralise. Precipitate formed. Concentrated under reduced pressure to remove ethanol. Residue extracted with DCM (3 × 10 mL). The extract was then adsorbed onto silica and purified by further chromatography (0.5% MeOH/DCM) to obtain yellow solid, PMY 14-3-B (8 mg, 2%). Total yield 12%.

PMY 14-3-A and -B consistent with PMY 16-1. Very minor trace of "grease" in ¹H NMR in -A and slightly more than -B. PMY 16-1 had major grease contamination. Currently investigating source, probably stock MeOH and DCM.

NMR:


Risk and Hazard Assessment:


See also:
Hydrolysis of acyl-iminothiazolidinone PMY 14-1 (PMY 16-1)
Synthesis of phenyliminothiazolidinone-substituted arylpyrrole (PMY 14-2)
Synthesis of phenyliminothiazolidinone-substituted arylpyrrole (PMY 14-1)
Preparation of 2-phenyliminothiazolidin-4-one (PMY 13-1)