The reactions of 5-pyrrolyl-pyrimidinyloxyacetaldehyde or methyl ketone with primary amines yielded hydroxymethylpyrrolopteridine derivatives via a cascade of iminium cyclization and O–N Smiles rearrangement. The present cascade exhibited a different profile compared to the previously reported ones, which consisted of N–N Smiles rearrangement. Lewis acid (TiCl4) under carefully controlled conditions was employed to suppress the ...