Polymer-Supported Synthesis of Mono-substituted Porphyrins

Significance

The authours have reported the selective synthesis of mono-substituted porphyrins on insoluble and soluble polymers. Polymer-supported porphyrins 2a and 2a′ were prepared on a soluble PS (1) and an insoluble PS (1′), respectively, via addition of pyrrole and benzaldehyde to polymers, followed by oxidation with DDQ and p-chloranil. After workup the polymer-bound products (2a and 2a′) underwent alkaline hydrolysis to give the mono-substituted tetraarylporphyrin 3a in 30% (from polymer 1) and 6% (from polymer 1′) overall yield, respectively. In the case of using the soluble polymer, the formation of an intermediate 2a was confirmed by ¹H NMR spectroscopy. The protocol with the soluble polymer was applied to prepare 3b (overall 16%) and 3c (overall 15%).