TCMDC_ArylPyrrole

 

Condensation of 2-phenyliminothiazolidin-4-one (PMY 13-1) and PMY 2-4 to obtain the iminothiazolidinone substituted 4-fluorophenylpyrrole analogue of "near neighbours".



Reaction start time: 15.30 11/10/11
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 refluxed in EtOH (15 mL). After 2 hours, TLC shows no reaction. After 20 hours, TLC shows no reaction. AcOH (approx 5 mL) added. After an hour, no reaction. Reaction concentrated and redissolved in AcOH (10 mL) and heated to 100 °C. No reaction after overnight reaction. Acetic anhydride (3 mL) added. After 3 hours reflux, reaction was poured over ice (125 mL). Green solid forms. EtOAc (100 mL) added and separated. The organic was washed with NaHCO₃ (3 × 25 mL), water (3 × 10 mL), brine and dried (MgSO₄) then concentrated under reduced pressure to a green foam (0.48 g). 19/10/11 Purified by chromatography (0-40% EtOAc/hexane) to obtain recov SM aldehyde (66 mg), late running product PMY 14-1-A (major fraction, contains minor impurity) and PMY 14-1-B (clean, 42 mg). PMY 14-1-A dissolved in hot EtOAc (approx. 20 mL) and cooled to -2 °C for 1 hour then filtered. The filtrate was concentrated under reduced pressure orange gum (46 mg). 14-1-A and B consistent with acylated product and Ethyl acetate. Filtered solid (PMY 14-1-A_solid) consistent with acylated product. Integrals still aren't perfect though, so some room for error/impurities here

m/z (ESI+) 392 [M+H]⁺, 40%; 434 [M+Ac+H]⁺, 85%; 456 [M+Ac+Na], 75%; 889 [2(M+Ac)]⁺, 100%.

Mass spec indicates Acetylated product formed, not intended product! ¹H NMR also consistent.



PMY 14-1-A, -A_solid and -B combined to make PMY 14-1-C and dried under vacuum with gentle heating to remove residual EtOAc. Yellow foam (137 mg, 34%).

TLC (10% MeOH/DCM) visualised with UV and vanillin:

Left to right: phenylthiourea, PMY 13-1, PMY 2-4, PMY 2-4/RM, RM, PMY 13-1/RM, PMY 13-1.

40% EtOAc/hexane

NMR:



IR:


Risk and Hazard Assessment:


References:

• doi:10.1016/j.bmc.2008.10.032
  
• doi:10.1016/S0040-4020(01)98392-9
  

See also:
Preparation of 2-phenyliminothiazolidin-4-one (PMY 13-1)