Mono-, bis- and tris-indolyl-substituted furanones useful as color formers, particularly in carbonless duplicating and thermal marking systems, which are prepared respectively by: the interaction of an indole with mucochloric acid; the interaction of an indole with a 4-mono(indolyl)-substituted 4-oxo-2-butenoic acid; and by the interaction of an indole with a 2,4-bis(indolyl)-substituted 4-oxobutanoic acid or with a 3,5-bis(indolyl)-substituted furanone.
单-, 双-, 和三-
吲哚取代的
呋喃酮可以作为颜色形成剂,在无碳复写和热标记系统中特别有用。这些化合物分别通过以下方法制备:
吲哚与
氯黏酸的反应;
吲哚与4-单(
吲哚基)-取代的4-氧代-
2-丁烯酸的反应;以及
吲哚与2,4-双(
吲哚基)-取代的4-氧代
丁酸或3,5-双(
吲哚基)-取代的
呋喃酮的反应。