A method of making a 5-formylporphyrin, comprises the steps of: condensing a 5-acetaldipyrromethane with a dipyrromethane-1,9-dicarbinol to produce a porphyrin having an acetal group substituted thereon at the 5 position; and then hydrolyzing said porphyrin to produce said 5-formylporphyrin. Products and intermediates useful in such methods, along with methods of making such intermediates, are also described.