1. Imidazo [1,2-a] pyridinium salts
2. The reaction of amines with 1-phenacyl-2-bromopyridinium salts. A new route to imidazo[1,2-.alpha.]pyridinium, oxazolo[3,2-.alpha.]pyridinium, and dihydropyrido[2,1-c]-as-triazinium salts
3. The effect of using α-chloroketones (rather than their α-bromo analogs) was not rigorously examined. However in refluxing acetone 2-(benzylamino)pyridine and α-chloroacetone afforded only IIIe whereas under similar conditions α-bromoacetone gave IIe or a mixture of IIe and IIIe. The replacement of acetone with higher boiling solvents was not examined.
4. In reference (2) a carbinolamine of type III was converted to an imidazo [1,2α] pyridinium salt (II) using either hot polyphosphoric acid and/or perchloric acid.
5. This appears to explain the observation in the original Bradsher apper that the misassigned bromide salts (compounds c, d, and f) all analyzed as monohydrates whereas their corresponding perchlorates analyzed as anhydrous materials; i.e. a dehydration must have occurred during perchlorate salt formation.