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Palladium(II)/Copper Halide/Solvent Combination for Selective Intramolecular Domino Reactions of Indolecarboxylic Acid Allylamides: An Unprecedented Arylation/Esterification Sequence
Author(s) -
Broggini Gianluigi,
Barbera Vincenzina,
Beccalli Egle M.,
Borsini Elena,
Galli Simona,
Lanza Giuseppe,
Zecchi Gaetano
Publication year - 2012
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201100614
Subject(s) - chemistry , indole test , intramolecular force , halogenation , palladium , nucleophile , halide , acetonitrile , solvent , medicinal chemistry , organic chemistry , combinatorial chemistry , catalysis
Intramolecular oxidative palladium‐catalyzed reactions of indolylallylamides in the presence of the couple bis(acetonitrile) palladium dichloride and copper(II) halide are described. Starting from 2‐ and 3‐indolylallylamides and involving in both cases the C‐3 position of the indole nucleus, variously substituted β‐carbolinones were obtained by arylation/halogenation, arylation/esterification or arylation/carboalkoxylation processes. On the other hand, an unusual aminohalogenation/halogenation sequence performed on 2‐indolylallylamides gave rise to pyrazino[1,2‐ a ]indole products. The carboesterification process is the result of an unknown path that involves the DMF or DMA used as solvent. The outcome of the reactions of the 3‐indolylallylamides arises from a totally selective 1,2‐migration of the acyl group on the supposed spiro intermediates formed from the nucleophilic attack of the C‐3 indole position.