Regioselective ß-silylation of porphyrins via iridium-catalyzed C-H bond activation.

An efficient approach to meso-unsubstituted ß-silylporphyrins was developed through highly regioselective Ir-catalyzed C-H activation, in the presence of HSiMe(OSiMe3)2 as the Si source, from meso-unsubstituted porphyrins. Further transformations of the silyl group, such as oxidation, halogenation, and cross-coupling reactions, could be achieved under mild conditions, demonstrating the synthetic utility of ß-silylporphyrins as a multipurpose synthon for fabricating porphyrin derivatives.

Palladium-catalyzed Kumada coupling reaction of bromoporphyrins with silylmethyl Grignard reagents: preparation of silylmethyl-substituted porphyrins as a multipurpose synthon for fabrication of porphyrin systems.

We have developed an efficient method for preparing silylmethyl-substituted porphyrins via the palladium-catalyzed Kumada cross-coupling reaction of bromoporphyrins with silylmethyl Grignard reagents. We demonstrated the synthetic utility of these silylmethylporphyrins as a multipurpose synthon for fabricating porphyrin derivatives through a variety of transformations of the silylmethyl groups, including the DDQ-promoted oxidative conversion to CHO, CH(2)OH, CH(2)OMe, and CH(2)F functionalities and the fluoride ion-mediated desilylative introduction of carbon-carbon single and double bonds.