title: Oxazolochlorins. 2. Intramolecular cannizzaro reaction of meso-tetraphenylsecochlorin bisaldehyde.
abstract: Using mildly basic reaction conditions, the periodate-induced diol cleavage of meso-tetraphenyl-2,3-diolchlorin allows for the generation and isolation of the corresponding hitherto elusive free base secochlorin bisaldehyde. An intramolecular Cannizzaro reaction of this porphyrinoid generates three pyrrole-modified, oxazole-based porphyrins: the known porpholactol (2-oxa-3-hydroxychlorin) as the major product, known porpholactone (2-oxa-3-oxoporphyrin), and a novel porpholactol dimer that is linked through an acetal functionality. The structure of the dimer was confirmed by (1)H NMR spectroscopy, X-ray diffractometry, and ESI(+) collision-induced fragmentation mass spectrometry. The chromophores in the dimer are coupled electronically only to a minor extent. A mechanism to rationalize the formation of all products is advanced.
authors.affiliation: Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Akhigbe
authors.forename: Claudia
authors.initials: C
authors.lastname: Ryppa
authors.forename: Matthias
authors.initials: M
authors.lastname: Zeller
authors.forename: Christian
authors.initials: C
authors.lastname: Brückner