Characterisation of 1,4-benzothiazine intermediates in the oxidative conversion of 5-S-cysteinyldopa to pheomelanins - Napolitano, A.; Costantini, C.; Crescenzi, O.; Prota, G. (Elsevier)
Under biologically relevant conditions, oxidation of 5-S-cysteinyldopa (1) to pheomelanins proceeds through the formation of the 1,4-benzothiazine 7 along with the 3-carboxy analogue 6 in much smaller amounts, as evidenced by isolation of the reduced forms 5 and 4 and by deuterium labelling experiments. | Under biomimetic conditions, oxidation of 5-S-cysteinyldopa (1) to pheomelanins proceeds through the formation of the 1,4-benzothiazine 7 and to a much lesser extent of the acid 6, both arising by the rearrangement with or without decarboxylation of the cyclic quinonimine 3.
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Keywords: V