Formation, structure, and reactivity of meso-tetraaryl-chlorolactones, -porpholactams, and -chlorolactams, porphyrin and chlorin analogues incorporating oxazolone or imidazolone moieties

Joshua Akhigbe, John Haskoor, Jeanette A. Krause, Matthias Zeller, Christian Brückner

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

Reaction of known meso-tetraarylporpholactone free bases 3, made from the corresponding porphyrins, with hydrazine produces three products: It converts the lactone functional group into an N-aminolactam moiety, generating porphyrin-like N-aminoporpholactams 8. It also reduces regioselectively the β,β′-double bond of the pyrrolic moiety opposite to the imidazolone in both the starting material and the N-aminoporpholactam, thus forming the chlorin-like chlorolactones 7 and N-aminochlorolactams 9. An equivalent set of reaction products is also derived from the reaction of porpholactones 3 with tosylhydrazide. Reductive N-N cleavage of the N-aminoporpholactams 8 generated the parent porpholactams 10. The molecular structures of all key compounds were shown by single crystal X-ray diffraction to be essentially planar. Porpholactam 10a can be converted in two steps (enolization and halogenation α to the imine, followed by reductive removal of the halogen) to known imidazoloporphyrin 5a, thus constituting the third independent pathway to replace a β-carbon of a tetraphenylporphyrin by a nitrogen. All these transformations show the flexibility of our 'porphyrin breaking and mending' strategy toward the synthesis of novel porphyrin and chlorin analogues incorporating non-pyrrolic heterocycles that carry functionalities at their periphery.

Original languageEnglish (US)
Pages (from-to)3616-3628
Number of pages13
JournalOrganic and Biomolecular Chemistry
Volume11
Issue number22
DOIs
StatePublished - Jun 14 2013
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry

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