Synthesis of N-substituted pyrrole and tetrahydroindole derivatives from alkenyl β-dicarbonyl compounds

✍ Scribed by Helena M.C Ferraz; Fernando L.C Pereira; Fátima S Leite; Marta R.S Nunes; M.Elena Payret-Arrúa

• Publisher: Elsevier Science
• Year: 1999
• Tongue: French
• Weight: 453 KB
• Volume: 55
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(99)00625-0

✦ Synopsis

The iodocyclization of a series of alkenyl-substituted p-enamino esters and ketones, followed by base-promoted dehydroiodination, led to the formation of the corresponding pyrrole or tetrahydroindole derivatives. In the absence of base, the iodo-I~-enamino esters 5 and 7 underwent spontaneous aromatization after dehydroiodination, furnishing the 4, 5, 6, 7-N-substituted-tetrahydroindoles 19 and 20.

All the elimination reactions proceeded smoothly, in yields ranging from 71% to 99%. Starting from the 13allyl-dimedone 21, it was possible to prepare the oxotetrahydroindole 24, in moderate overall yield.