Vilsmeier-Haack formylation of Cu(II) and Ni(II) porphyrin complexes under microwaves irradiation

Microwave irradiation is a powerful tool in organic synthesis allowing for instance, to reduce reaction times and to obtain the desired products in better yields. Contrary to what is reported in literature, the first Vilsmeier-Haack formylation of Ni(II) and Cu(II) complexes of meso-tetraarylporphyrins by using microwave irradiation is described here. Different solvents, irradiation powers and reaction times were studied using the Ni( II) and Cu( II) complexes of 5,10,15,20-tetraphenylporphyrin and the best found conditions were extended to a series of other meso-substituted tetraarylporphyrins. The products, namely the new ones were isolated in good to excellent yields and with a significant reduction on the reaction times. Scaled-up studies have shown that the efficiency of the process is not affected by increasing the amount of porphyrin.