3-(Indolyl)-Phthalides and (2-Carboxybenzyl)-Indoles

Wayland E. Noland, James Elver Johnson

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9 Scopus citations

Abstract

New chemical and spectral evidence is presented concerning the structures of phthalides derived from fusion of indoles with phthalaldehydic or opianic acids. The phthalides derived from indole and 7-methylindole are assigned the 3-substituted indole structures Ia, If and Ib, Ig. The phthalides derived from skatole and its derivatives are reassigned the 1-substituted indole structures IIa–IIf. The phthalide derived from 2-methylindole and opianic acid, about which conflicting reports appear in the literature, is assigned the 3-substituted indole structure Ih, analogous to the phthalide (Ic) from 2-methylindole and phthalaldehydic acid. New phthalides are described from the reactions of phthalaldehydic acid with 1-methylindole (Id), 1,2-dimethylindole (Ie), 2,3-dimethylindole (IIg) and 1,3-dimethylindole (IIIg). The structures of all the products studied indicate that the tendency to form phthalides at available positions of the indole nucleus is in the order 3 > 1 > 2. Structures VIII and possibly IX are proposed for by-products from the reactions of phthalaldehydic acid with 1-methylindole and skatole, respectively. The (indolyl)-phthalides have been found to undergo hydrogenolysis under low pressure hydrogenation. This constitutes a general synthetic route to (2-carboxybenzyl)-indoles of all three types: 1-, 2- and 3-substituted indoles.

Original languageEnglish (US)
Pages (from-to)5143-5147
Number of pages5
JournalJournal of the American Chemical Society
Volume82
Issue number19
DOIs
StatePublished - Oct 5 1960

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