<i>meso</i>-Arylporpholactones and their Reduction Products
作者:Christian Brückner、Junichi Ogikubo、Jason R. McCarthy、Joshua Akhigbe、Michael A. Hyland、Pedro Daddario、Jill L. Worlinsky、Matthias Zeller、James T. Engle、Christopher J. Ziegler、Matthew J. Ranaghan、Megan N. Sandberg、Robert R. Birge
DOI:10.1021/jo300963m
日期:2012.8.3
chlorin 7 is prepared from the parent porphyrin 1, this amounts to a 2-step replacement of a pyrrole moiety in 1 by an oxazolone moiety. The stepwise reduction of the porpholactone 5 results in the formation of chlorin analogues, meso-tetraaryl-3-hydroxy-2-oxachlorin (11) and meso-tetraaryl-2-oxachlorins (12). The reactivity of 11 with respect to nucleophilic substitution by O-, N-, and S-nucleophiles
Elucidation of the extraordinary 4-membered pyrrole ring-contracted azeteoporphyrinoid as an intermediate in chlorin oxidation
作者:Tillmann Köpke、Maren Pink、Jeffrey M. Zaleski
DOI:10.1039/b611567e
日期:——
Reaction of 2,3-dioxochlorins with benzeneselenic anhydride (BSA) results in the formation of unusual ring-contracted azetine derivatives that further react with BSA to afford porpholactones.
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 all acetal functionality. The structure of the dimer was confirmed by H-1 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.