1,3,4,5-Tetrahydrobenz[cd]indoles and related compounds. Part I. A new synthesis of 3,4-dihydrobenz[cd]indol-5(1H)-one (Uhle's ketone)
Abstract
New syntheses of 4-carboxyindole-3-propionic acid (9) starting from 3-amino-4-chlorobenzoic acid are described. A process involving thermal decarboxylation of 2,4-dicarboxyindole-3-propionic acid (8) in aqueous alkali is shown to be suitable for the large-scale preparation of the diacid (9) and thence Uhle's ketone (1).