Poster presentation, P6

Official XXIst International Pigment Cell Conference website - 21-24 Sept 2011, Bordeaux - France | updated: September 04 2011

Synthetic routes to 5,6-Dihydroxyindole oligomers: a tool for the bottom-up approach to eumelanin stucture

5,6-Dihydroxyindole (DHI) derived oligomers provide a most powerful investigative tool to elucidate the structure and physical/chemical properties of eumelanin and to unravel the complex process of supramolecular aggregation via a bottom up approach.^1-4 Until a few years ago access to DHI oligomers was based almost exclusively on controlled oxidative polymerization processes. However, several limitations inherent to the diverse bonding patterns in DHI coupling and the ensuing complexity of the reaction mixtures, prevented this approach from reaching a synthetic status. Herein we report a convenient synthetic entry to DHI oligomers as the acetyl derivatives, including dimers (1-Ac, 2-Ac, 3-Ac),⁵ a trimer (4-Ac)⁶ and a tetramer (5-Ac). The approach is based on a unified procedure involving ortho-ethynylanilines as key intermediates. 1. P. Meredith and T. Sarna, Pigment Cell Melanoma Res., 2006, 19, 572-594. 2. M. d’Ischia, A. Napolitano, A Pezzella, P. Meredith and T. Sarna, Angew. Chem. Int. Ed., 2009, 48, 3914-3921. 3. A. Pezzella, A. Iadonisi, S. Valerio, L. Panzella, A. Napolitano, M. Adinolfi and M. d'Ischia, J. Am. Chem. Soc., 2009, 131, 15270-15275.4., J. P. Bothma, J. de Boor, U. Divakar, P. E. Schwenn, P. Meredith, Adv. Mat., 2008, 20, 3539-42. 5. L. Capelli, P. Manini, A. Pezzella, A. Napolitano and M. d'Ischia, J. Org. Chem., 2009, 74, 7191-7194. 6. L. Capelli, P. Manini, A. Pezzella, and M. d'Ischia Org. Biomol. Chem., 2010, 8, 4243 - 4245

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