2,4,6-Trimethylpyridine → HCID 178435492, compound

Participants

Reaction Steps

Methyl pheophorbide-a (15.8 g, 26.0 mmol) was added to commercially available 2,4,6-collidine (1.5 L, Aldrich), and the mixture was heated to reflux with stirring. After 30 hours of reflux, the reaction was still incomplete by TLC and HPLC and a heavy baseline was observed. The solution was cooled to room temperature and solvent removed under reduced pressure. The residue was first precipitated twice from methylene chloride/methanol, then purified on a silica gel column with 10% ethyl acetate/methylene chloride. TLC of the desired fraction showed presence of methyl pheophorbide and a heavy baseline. After evaporating off the solvent, the residue was dissolved in 2,4,6-collidine (500 mL) and heated to reflux again. After 2 days of reflux, TLC of the reaction solution still showed the presence of methyl pheophorbide. The reaction solution was evaporated to dryness and the residue was purified on a silica gel column. The desired fraction was evaporated to dryness and the residue was redissolved in methylene chloride, precipitated twice with methanol, and finally purified on a silica gel flash column to give 3.4 g of methyl pyropheophorbide-a.

Provenance & Evidence