synthesis of 2-formylpyrroles from pyridinium salts is reported. This protocol enables the synthesis of diversely substituted 2-formylpyrroles in good yields under operationally simple conditions. The detailed mechanistic studies reveal that the reaction proceeds via a novel H2O-triggered ring opening of the pyridinium salt and a subsequent intramolecularly nucleophilic addition sequence.
The present invention is directed to an optical recording medium having at least a recording layer and a reflective layer on a substrate, said recording layer containing a dipyromethene metal chelate compound obtained from a dipyromethene compound represented by the general formula (1) and a metal ion:
wherein R1 to R7 are defined in the specification.