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Ultra‐low Temperature Oxidation of 5,6‐Dihydroxyindole: A Novel Approach to Study Synthetic Melanogenesis †
Author(s) -
Hatcher Lanying Q.,
Simon John D.
Publication year - 2008
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.2008.00348.x
Subject(s) - chemistry , dimer , semiquinone , pigment , melanin , photochemistry , copper , stereochemistry , organic chemistry , redox , biochemistry
The detailed structure of melanin remains elusive due to the complexity and insolubility of the pigment. Herein we describe a novel oxidation of 5,6‐dihydroxyindole (DHI) as a means to characterize soluble intermediates formed prior to oligomerization. The approach entails the use of a biomimetic copper‐peroxo oxidant, at ultra‐low temperature (−78°C). DHI oxidized by [LCu II (O 2 )Cu II L]B(C 6 F 5 ) 4 ( L = 2,6,10‐trimethyl‐2,6,10‐triazaundecane) under argon produces the one electron oxidation product, semiquinone radical, which is spectroscopically observed at −78°C. MS analysis of the reaction mixture reveals the DHI dimer as well as other extensively oxidized DHI units.