Chemistry of Novel Non-Aromatic, Meso-Alkylidenyl Carbaporphyrinoids

We developed new class of porphyrinoids and core-modified porphyrinoids that have not been well studied previously. So called, meso-alkylidenyl porphyrins and their congeners are rather recently developed porphyrinoid family that have shown several unique properties including tautomerization, unusual protonation selectivity and spectroscopic properties. We here report the chemistry of meso-diethyl malonylidene-(m-benzi)porphyrin and meso-diethyl malonylidene-(m-benzi)pentaphyrins such the reaction with in-situ generated azomethine ylides and redox reactions. This 1,3-dipolar cycloaddition reaction has well documented and become an important alternative to the synthesis of pi-extended porphyrin analogs. The versatility and synthetic utilities associated with these reactions is useful in the synthesis of pi-extended analogs of the meso-alkylidenyl porphyrinoids. Successive 1,3-dipolar cycloaddition reaction combined with oxidation could be good tool for the pi-extended porphyrin analogs bearing region-selectively fused pyrrole rings. The 1,3-dipolar cycloaddition of the corresponding Pd(II) complexes also resulted in bis-cyclized adducts which are resistant to DDQ oxidation. All adducts are liable to core N-methylation. The adducts exhibit large bathochromic shift of absorption.

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