Studies related to the chemistry of melanins. Part VII. Attempts to synthesise hydroxylated bi-indolyls, biphenyls, and indoline-2-carboxylic acid as possible intermediates in the formation of melanins from 3,4-dihydroxyphenethylamine and 3,4-dihydroxyphenylalanine
Abstract
Syntheses are described of 5,5′-, 6,6′-, and 5,6′-bis-(2-aminoethyl)-2,2′,3,3′-tetrahydroxybiphenyl, 2,4-bis-(3,4-dihydroxyphenyl)butane-1,3-diamine, and 2,3-bis-(3,4-dihydroxyphenyl)butane-1,4-diamine dihydrochlorides, 5,5′-, 6,6′-, and 5,6′-bis-(2-amino-2-carboxyethyl)-2,2′,3,3′-tetrahydroxybiphenyl, and 5,6-dihydroxyindoline-2-carboxylic acid.