Pyrrole → HCID 136044060, compound

Participants

Reaction Steps

1,4,5-Trimethylimidazole-2-carboxaldehyde (37, 750 mg, 5.42 mmol), prepared according to literature procedure (Alcalde, E. et al., Tetrahedron 52:15171-15188 (1996)), was dissolved in propionic acid (120 mL) in a 250 mL three neck round-bottom flask equipped with a thermometer and a condenser. The solution was heated to reflux then pyrrole (0.38 mL, 5.42 mmol) was added. The reaction mixture was heated at reflux for an additional 5 h, then cooled to room temperature while exposed to air overnight. The propionic acid was removed by vacuum distillation yielding a dark solid residue which was adsorbed onto silica gel. Purification by column chromatography (gradient elution 5-10% MeOH/CH2Cl2) provided porphyrin 38 as a mixture of atropisomers (108 mg, 10.7%). 1H NMR (300 MHz, CDCl3)*−2.90, −2.85, −2.78 (3 s, 2H, atropisomer NH), 2.50 (s, 12 H), 2.57 (s, 12 H), 3.15-3.42 (multiple s, 12 H, atropisomer N—CH3), 8.91 (multiple s, 8 H, atropisomer).

Provenance & Evidence