2-furanones and preparation thereof

Abstract From the Canadian patent

3,5-Bis- and 3,5,5,-tris-indolyl-2-(5H)-furnanones 3,4-dichloro-5-mono or 5-bis-indolyl-2(5H)-furnanones and 3,5bis-indolyl-2-(3H)-furnanones which may bear hydrocarbon Hor 2-substituents on the indolyl groups and which are useful as color formers, particularly in carbonless duplicating and thermal marking systems, which are prepared respectively by the interaction of an indole with sucochloric acid; the interaction of an indole with a 4-mono(indolyl)substituted 4-oxo-2-butanoic 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 furnanone.