Improved syntheses of 6‐hydroxy‐5‐methoxy‐ and 5‐hydroxy‐6‐methoxyindoles and their O‐acetates, analogs of natural eumelanin precursors

Abstract

AbstractImproved routes for syntheses of gram quantities of the isomeric 5,6‐acetoxymethoxyindoles, and milligram amounts of the 5,6‐hydroxymethoxyindoles, have been developed. They depend on regiospecific nitration of the benzyl ethers of vanillin and isovanillin as the first steps. Improved condensations of 4,5‐acetoxymethoxy‐2‐nitrobenzaldehydes with nitromethane gave 4,5‐acetoxymethoxy‐2,β‐dinitrostyrenes as the key intermediates to all four indoles.