Tunable Pd-catalyzed cyclization of indole-2-carboxylic acid allenamides: carboamination vs microwave-assisted hydroamination.
A variety of 3-vinyl-substituted imidazo[1,5-a]indole derivatives were synthesized by intramolecular Pd-catalyzed cyclization of the title allenamides through either a domino carbopalladation/exo-cyclization process or a novel hydroamination reaction that proceeds smoothly under microwave irradiation. Both the observed pathways involve a π-allyl-palladium(II) complex arising from insertion of the allene group into a palladium(II) species, the latter being formed in situ by the intervention of an aryl iodide or of the N-H group. In both cases, the role of nucleophile is covered by the indole nitrogen.
Beccalli
Egle M
EM
DISMAB, Sezione di Chimica Organica A. Marchesini, Università di Milano, via Venezian 21, 20133 Milano, Italy.
Bernasconi
Alice
A
Borsini
Elena
E
Broggini
Gianluigi
G
Rigamonti
Micol
M
Zecchi
Gaetano
G
D000577:Amides / Q000138:chemical synthesis* / Q000737:chemistry; D000586:Amination; D002264:Carboxylic Acids; D002384:Catalysis; D003500:Cyclization; D007211:Indoles / Q000737:chemistry*; D008872:Microwaves; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry*; D013237:Stereoisomerism
D000577:Amides; D002264:Carboxylic Acids; D007211:Indoles; C058980:indole-2-carboxylic acid; D010165:Palladium