Base-promoted rearrangements of ester groups in 3a,7a-dihydroindole-2,3,3a,4-tetraester

✍ Scribed by Kyu Ok Jeon; Ji Sook Yu; Chang Kiu Lee

• Publisher: Journal of Heterocyclic Chemistry
• Year: 2007
• Tongue: English
• Weight: 413 KB
• Volume: 44
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570440522

✦ Synopsis

Abstract

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Tetramethyl 3a,7a‐dihydro‐1‐methyl‐1__H__‐indole‐2,3,3a,4‐tetracarboxylate which is an 1:2 adduct of 1‐methylpyrrole and dimethyl acetylenedicarboxylate underwent isomerization catalyzed by sodium methoxide to form a 5,7a‐dihydro‐1‐methyl‐1__H__‐indole‐2,3,4,5‐tetracarboxylate, its 5,6‐dihydro isomer, and a ring opening product which is an azonine derivative. Fully aromatized esters such as 1‐methylindole‐2,3,4‐triester, 1‐methylindole‐2,3,4,5‐tetraester and 1‐methyl‐2,3,4,6‐tetraester were also isolated. An indole compound which could be formed by conjugative addition of the methoxide ion was also isolated.